This is doc/epl.info, produced by makeinfo version 4.0 from doc/epl.texi. INFO-DIR-SECTION Emacs START-INFO-DIR-ENTRY * EPL: (epl). Script Emacs with Perl. END-INFO-DIR-ENTRY This Info file documents EPL, an Emacs extension that supports the use of Perl to write other Emacs extensions. Copyright (C) 2001 John Tobey This edition is for EPL version 0.7, 13 January 2001. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".  File: epl.info, Node: Top, Next: Preface, Up: (dir) EPL *** This is edition 0.2 of the EPL Reference Manual, corresponding to EPL version 0.7. EPL (Emacs Perl) is a library of Lisp functions and Perl modules that let you write Emacs extensions in Perl. * Menu: * Preface:: Why I'm here. * Introduction:: Beginning with an example. * Features:: How Perl looks to Lisp, how Lisp looks to Perl. * Configuration:: Changing the defaults. * Internals:: What happens under the hood. Appendices * Copying Conditions:: The GNU Free Documentation License. * Index:: Index to this manual. --- The Detailed Node Listing --- Introduction to EPL * Perl Example:: An example: Find files containing regex. * History:: EPL uses IPC, not translation or embedding. * Emacs Lisp:: You need the Emacs Lisp Reference Manual. * Coding Conventions:: Why the Perl examples use `&FUNCTION()'. How Language Features Correspond * Data Conversion:: Working with each other's data types. * Functions:: Transfering program control. * Control Structures:: Exceptions; `throw', `signal', `die'. * Input/Output:: Perl's primitives are redefined in Emacs. * Caveats:: It's not always a happy marriage. Configuration * Installation:: Lisp files, Perl modules, documentation. * The Easy Way:: We like the defaults. * Starting a Perl Process in Emacs:: `make-perl-interpreter'. * Starting an Emacs Process in Perl:: `use Emacs;'. Internals * Debugging Options:: Dumping traffic to stderr or a buffer. * Transport Layer:: Media of interprocess communication. * Message Types:: What interpreters can say to each other. * State Transitions:: The message stream grammar. * Protocol:: Current EPL protocol (*subject to change*).  File: epl.info, Node: Preface, Next: Introduction, Prev: Top, Up: Top Preface ******* Like a lot of people, I learned Perl because of the Web. I came to GNU from a Microsoft background early in 1996, when Microsoft had only begun to realize that the Internet was hot. I was deeply infused with Web hype, willing to try something different, and aware that the Web ran on Unix and Perl. I came to Emacs because of genetic predisposition. A tightly integrated, yet versatile, complex system with endless opportunities for learning and automation helps reduce my cholesterol and, I think, aids respiration and digestion. It had all the good features of Microsoft Office, without all the headaches and nausea. Well, it had _almost_ all the good features. Emacs is an oasis of integration in the chaotic and disparate realm of Linux and Unix. (I later learned that the Unix kernel is a thing of some elegance, but at the level of `/etc/resolv.conf', X11R6, and `~/.fvwmrc', there was little cohesion.) As I entered this realm, it irked me that I had to learn _two_ scripting languages to do what I wanted, whereas Visual Basic, clunky as it is, does everything on Windows. Speaking of that other--umm--language, Visual Basic shares an important feature with Perl: It is for ordinary people. Now, I am very glad that Emacs lets you do just about anything with Elisp (such as write EPL). But my conceptual mapping from Windows onto Unix paired Visual Basic with Perl, not Lisp, as the general workhorse get-it-done tool. It seemed to me not right that the standard, full-featured editor on my new system could not understand the standard, full-featured scripting language. With EPL--Emacs PerL, or Emacs-Perl-Lisp--I hope to rectify the situation.  File: epl.info, Node: Introduction, Next: Features, Prev: Preface, Up: Top Introduction ************ EPL is an extension for GNU Emacs (http://www.gnu.org/software/emacs/) and XEmacs (http://www.xemacs.org) that lets you write commands in Perl. It is also a programming interface for Elisp (*note Emacs Lisp::) programs to use Perl features and an interface for Perl to use Emacs. This document assumes knowledge of Emacs terms such as "the minibuffer" and "`M-x'" (*note Running Commands by Name: (emacs)Top.). It assumes knowledge of Perl references and nested data structures (perlref(1)), and packages and modules (perlmod(1)). * Menu: * Perl Example:: An example: Find files containing regex. * History:: EPL uses IPC, not translation or embedding. * Emacs Lisp:: You need the Emacs Lisp Reference Manual. * Coding Conventions:: Why the Perl examples use `&FUNCTION()'.  File: epl.info, Node: Perl Example, Next: History, Up: Introduction Perl Example ============ Let's illustrate EPL with an example. Suppose you often want to edit many files in the same directory based on some text that they contain. You want a command that will look for a specified regular expression in each file, and if found, open the file in a buffer. You prefer Perl regular expressions to Emacs ones, and you are not interested in files that Perl considers to be binary. Here is some Emacs Perl code that will do it: use IO::Dir; use IO::File; sub find_my_files ($$) { my ($dirname, $regex) = @_; # Convert "~" to home dir. $dirname = &expand_file_name ($dirname); my $dh = IO::Dir->new ($dirname) or die "$dirname: $!"; my $count = 0; while (defined ($filename = $dh->read)) { $filename = "$dirname/$filename"; # Skip directories and binary files. next unless -f($filename) && -T($filename); my $fh = IO::File->new ($filename); if (!$fh) { warn ("$filename: $!"); next; } while (defined ($_ = <$fh>)) { if (/$regex/) { &find_file($filename); $count++; last; } } } &message ("Found $regex in $count file(s)"); } defun (\*find_files_containing_regex, "Open all files whose contents match a Perl regular expression.", interactive("DLook in directory: \nsPerl regex: "), \&find_my_files); You would save this in a file, load it with `M-x perl-load-file' (*note Evaluation::) or from `~/.emacs', and use it as `M-x find-files-containing-regex'. The command prompts for a directory name (with -completion and history) and an arbitrary string (regex). It signals an error if it can't read the directory, and otherwise summarizes the results in the minibuffer. You can access its documentation just like that of any Emacs command, using `C-h f find-files-containing-regex'.  File: epl.info, Node: History, Next: Emacs Lisp, Prev: Perl Example, Up: Introduction History ======= EPL works by starting a subprocess the first time a Perl interpreter is needed to carry out some function. Emacs and Perl use interprocess communication (IPC) to invoke functions and send each other data until the parent process terminates. Variations on this theme may involve Perl as the parent process or more than one child per parent. This is not the only possible implementation. In principle, the same functionality could be achieved by translating Perl to Lisp. That has been a goal of the GNU project since 1994, except that RMS wants to replace Elisp with Scheme first. For details, see *Note Lisp History: (elisp)Lisp History, and `http://www.vanderburg.org/Tcl/war/'. Another possibility, which has been realized by a program called Perlmacs (http://john-edwin-tobey.org/perlmacs/), is to embed the Perl interpreter in Emacs and let it operate directly at the C level the way the Elisp interpreter does. This probably results in faster execution, but it ties an executable to specific versions of Perl and Emacs. Perlmacs does not support XEmacs.  File: epl.info, Node: Emacs Lisp, Next: Coding Conventions, Prev: History, Up: Introduction Emacs Lisp ========== Whether you write EPL programs or Elisp programs, you are writing Emacs programs. The GNU and XEmacs projects maintain comprehensive and thorough documentation of the functions available to Emacs extensions. Of course, those documents assume that extensions use Lisp. Still, they are an invaluable resource, and any programmer with a general understanding of functions and variables can make good use of them. This manual makes frequent reference to the *Note GNU Emacs Lisp Reference Manual: (elisp)Top. If you don't have it, go get it! It should be available wherever you got Emacs or from the Free Software Foundation (http://www.gnu.org/doc/doc.html). Who knows? You may fall in love with Lisp.  File: epl.info, Node: Coding Conventions, Prev: Emacs Lisp, Up: Introduction Coding Conventions ==================  File: epl.info, Node: Features, Next: Configuration, Prev: Introduction, Up: Top Features ******** This chapter describes EPL's mapping between Perl's language features and Emacs Lisp's. Perl and Lisp are quite different, so some features favored by one language are imperfectly or awkwardly reproduced in the other. EPL follows Perl's philosophy of making simple things easy and hard things possible. * Menu: * Data Conversion:: Working with each other's data types. * Functions:: Calling each other's functions, `defun'. * Control Structures:: Exceptions; `throw', `signal', `die'. * Input/Output:: Perl's primitives are redefined in Emacs. * Caveats:: It's not always a happy marriage.  File: epl.info, Node: Data Conversion, Next: Functions, Up: Features Data Conversion =============== EPL provides essentially two mechanisms to transfer data between languages--as function arguments and return values. In both cases, data may be passed either by value or by reference. The default is by value, since references incur overhead (*note References Incur Overhead::). In EPL, "by value" means recursively (or "deeply") copied. That is, containers in the originating language are converted to analogous containers in the destination language, and any contained elements not explicitly marked as pass-by-reference are likewise converted. This allows the recipient to examine a structure using its built-in accessors, but changes will not apply to the original. Also, language peculiarities result in information loss during some conversions, so pass-by-value is not completely reversible (*note Conversion Is Imperfect::). This section describes the conversions that apply to each language's scalar and container types. For a complete description of Lisp types, see *Note Lisp Data Types: (elisp)Lisp Data Types. * Menu: * Scalars:: Lisp has three scalar types. * The Null Value:: `undef' and `()' are `nil'. * Symbols and Globrefs:: `\*::sym' is `'sym'. * Lists and Arrayrefs:: `["fnord"]' is `'("fnord")'. * Vectors:: `\[42]' is `[42]'. * Conses:: The `Emacs::Lisp::Cons' type. * Scalar References:: The `perl-ref' type. * Code References:: `\&frob' is a lambda expression. * Hash Tables:: Not yet implemented. * Blessed References:: Not yet implemented. * Emacs Types:: Not yet implemented.  File: epl.info, Node: Scalars, Next: The Null Value, Up: Data Conversion Scalars ------- Lisp integers, floats, and strings all become Perl scalars. A simple Perl scalar becomes either an integer, a float, or a string. Unfortunately, it is hard to be certain which type will be chosen. It depends on the value. Perl 5.005 and later can distinguish among the literal constants `1', `"1"', and `1.0', and EPL uses this information. However, not all Perl integers fit into an Emacs integer (which is 28 bits, *note Integer Type: (elisp)Integer Type.). Integers that would overflow are upgraded to floats when converted. You _may_ be able to specify string conversion by wrapping a variable in double quotes (`"$var"'), float by adding zero (`$var + 0'), and integer using (`int($var)'). Perhaps a future version of EPL will provide an explicit means of specification. Interesting character encodings such as UTF-8 are not currently supported. All strings are considered unibyte. *Note Text Representations: (elisp)Text Representations.  File: epl.info, Node: The Null Value, Next: Symbols and Globrefs, Prev: Scalars, Up: Data Conversion The Null Value -------------- As an exception to the rule for symbols (*note Symbols and Globrefs::), `nil' in Lisp corresponds to `undef' in Perl. In Lisp, `nil' is really a symbol. However, it is typically used as the boolean value FALSE. Perl symbols (glob references) evaluate to TRUE in boolean context. It is very natural to convert `nil' to `undef'.  File: epl.info, Node: Symbols and Globrefs, Next: Lists and Arrayrefs, Prev: The Null Value, Up: Data Conversion Symbols and Globrefs -------------------- Glob references become symbols in Lisp. Underscores are swapped with hyphens in the name, since Perl prefers underscores and Lisp prefers hyphens.  File: epl.info, Node: Lists and Arrayrefs, Next: Vectors, Prev: Symbols and Globrefs, Up: Data Conversion Lists and Arrayrefs ------------------- Lists are a central data structure in Lisp. To make it as easy as possible to pass lists to Lisp functions that require them, Perl array references are converted Lisp lists. For example, the Perl expression ["x", ["y", 1]] is converted to '("x" ("y" 1)) in Lisp. Note, however, that the empty list in Lisp is indistinguishable from `nil', so it becomes the undefined value, not an arrayref. *Note The Null Value::.  File: epl.info, Node: Vectors, Next: Conses, Prev: Lists and Arrayrefs, Up: Data Conversion Vectors ------- Adding `\' to an arrayref makes it an arrayref ref, which EPL treats as a vector in Lisp. For example, Perl `\[1, 2, []]' becomes Lisp `[1 2 nil]'.  File: epl.info, Node: Conses, Next: Scalar References, Prev: Vectors, Up: Data Conversion Conses ------ Conses that are not lists become Emacs::Lisp::Cons objects. *Compatibility note:* In Perlmacs, such conses become opaque objects (*note Pass-by-Reference::). $x = &cons("left", "right"); print ref($x); # "Emacs::Lisp::Cons" print $x->car; # "left" print $x->cdr; # "right" But: $x = &cons ("top", undef); # a Lisp list print ref($x); # "ARRAY" print $x->[0]; # "top"  File: epl.info, Node: Scalar References, Next: Code References, Prev: Conses, Up: Data Conversion Scalar References -----------------  File: epl.info, Node: Code References, Next: Hash Tables, Prev: Scalar References, Up: Data Conversion Code References ---------------  File: epl.info, Node: Hash Tables, Next: Blessed References, Prev: Code References, Up: Data Conversion Hash Tables ----------- The issue with hash tables is that Perl's built-in ones permit only string keys. Right now, hash tables are passed by reference (*note Pass-by-Reference::).  File: epl.info, Node: Blessed References, Next: Emacs Types, Prev: Hash Tables, Up: Data Conversion Blessed References ------------------  File: epl.info, Node: Emacs Types, Prev: Blessed References, Up: Data Conversion Emacs Types -----------  File: epl.info, Node: Functions, Next: Control Structures, Prev: Data Conversion, Up: Features Functions ========= * Menu: * Evaluation:: `perl-eval'. * Ordinary Functions:: `perl-call', `use Emacs::Lisp;'. * Pass-by-Reference:: How to inhibit data conversion. * Commands:: Extending Emacs without Lisp, `defun'.  File: epl.info, Node: Evaluation, Next: Ordinary Functions, Up: Functions Evaluation ---------- - Function: perl-eval string &optional context This function parses and executes STRING as Perl code and returns its converted value (*note Data Conversion::). CONTEXT can specify an evaluation context (see perlsub documentation (http://www.perldoc.org)) and affects how the results are returned. It may be: `scalar-context' Evaluate in scalar context and return the result as a Lisp object. This is the default if CONTEXT is not given. `list-context' Evaluate in list context and return the result as a list. `void-context' Evaluate in void context and return `nil'. - Function: perl-eval-raw string &optional context This function executes STRING like `perl-eval' but does not convert its value. Instead, it returns a `perl-value' object that keeps a reference to a value in Perl.  File: epl.info, Node: Ordinary Functions, Next: Pass-by-Reference, Prev: Evaluation, Up: Functions Ordinary Functions ------------------ - Function: perl-call sub &rest arguments This function calls the Perl subroutine named SUB with ARGUMENTS and returns its value. If the first argument is `scalar-context', `list-context', or `void-context', it is not passed to the sub but affects the calling context as in `perl-eval'. *Note Evaluation::.  File: epl.info, Node: Pass-by-Reference, Next: Commands, Prev: Ordinary Functions, Up: Functions Pass-by-Reference ----------------- XXX Rewrite. A "shallow copy" simply wraps a Perl scalar in a Lisp object or vice versa. Wrapped Perl values appear as a Lisp objects of type `perl-value'. Wrapped Lisp values appear in Perl as objects of class `Emacs::Lisp::Object'. *Note References Incur Overhead::, for issues relating to wrapped data. In Perl, the `wrap' function wraps its argument in a Lisp object. This allows Perl data such as arrays to be passed by reference to Lisp functions. Another way Lisp can obtain references to Perl data is by using `perl-eval-raw' or `perl-call-raw'. Lisp can tell whether an object refers to Perl data by using the `perl-value-p' function. Of course, `wrap' is a Perl function, so the value it returns is really its argument wrapped in a Lisp object wrapped in a Perl object. But when you pass this object to Lisp as an argument or function return value, Lisp gets a reference to the original object, and no automatic conversion occurs. Lisp may explicitly convert it at any time using the `perl-to-lisp' function, and any changes made by Perl will be visible at the time of conversion. The Lisp function `perl-wrap' is the counterpart of Perl's `wrap' function, and the `Emacs::Lisp::Object' package provides the equivalent of `perl-call-raw'. The functions of package `Emacs::Lisp' return deep copies of Lisp function return values (see *note Functions::). However, the corresponding `Emacs::Lisp::Object' functions return references to live Lisp objects. Since a wrapped Lisp object appears in Perl as an `Emacs::Lisp::Object' blessed reference, if follows that it can be used with method syntax to invoke a function and pass itself as the first argument. Thus, supposing `v' is a vector of conses and `$v' is its wrapper, this Perl code $v->aref(3)->setcdr(t); has the effect of the following Lisp: (setcdr (aref v 3) t) An Emacs::Lisp::Object's `to_perl' method performs a deep copy and is the counterpart of `perl-to-lisp'. Lisp functions called through package Emacs::Lisp convert their return values using deep copying. The same functions are accessible through Emacs::Lisp::Object, which does shallow conversion and always returns an Emacs::Lisp::Object object. These examples show how the data wrapping functions work in Perl: $x = wrap [1, 2, 3]; print ref($x); # "Emacs::Lisp::Object" print ref($x->to_perl); # "ARRAY" print @{&list(2, 3)}; # "23" $x = Emacs::Lisp::Object::list(2, 3); print ref($x); # "Emacs::Lisp::Object" print @{$x->to_perl}; # "23" And in Lisp: XXX  File: epl.info, Node: Commands, Prev: Pass-by-Reference, Up: Functions Commands --------  File: epl.info, Node: Control Structures, Next: Input/Output, Prev: Functions, Up: Features Control Structures ==================  File: epl.info, Node: Input/Output, Next: Caveats, Prev: Control Structures, Up: Features Input/Output ============  File: epl.info, Node: Caveats, Prev: Input/Output, Up: Features Caveats ======= * Menu: * References Incur Overhead:: Memory management hurdles. * Conversion Is Imperfect:: Natural mappings are not always 1-to-1.  File: epl.info, Node: References Incur Overhead, Next: Conversion Is Imperfect, Up: Caveats References Incur Overhead -------------------------  File: epl.info, Node: Conversion Is Imperfect, Prev: References Incur Overhead, Up: Caveats Conversion Is Imperfect -----------------------  File: epl.info, Node: Configuration, Next: Internals, Prev: Features, Up: Top Configuration ************* * Menu: * Installation:: Lisp files, Perl modules, documentation. * The Easy Way:: We like the defaults. * Starting a Perl Process in Emacs:: `make-perl-interpreter'. * Starting an Emacs Process in Perl:: `use Emacs::Lisp;'.  File: epl.info, Node: Installation, Next: The Easy Way, Up: Configuration Installation ============  File: epl.info, Node: The Easy Way, Next: Starting a Perl Process in Emacs, Prev: Installation, Up: Configuration The Easy Way ============  File: epl.info, Node: Starting a Perl Process in Emacs, Next: Starting an Emacs Process in Perl, Prev: The Easy Way, Up: Configuration Starting a Perl Process in Emacs ================================  File: epl.info, Node: Starting an Emacs Process in Perl, Prev: Starting a Perl Process in Emacs, Up: Configuration Starting an Emacs Process in Perl =================================  File: epl.info, Node: Internals, Next: Copying Conditions, Prev: Configuration, Up: Top Internals ********* This chapter introduces the concepts involved in supporting single-threaded distributed exception handling and garbage collection for languages like Perl and Emacs Lisp. These languages have a lot more in common underneath than meets the eye. The chapter ends with a more concrete description of EPL's protocol. This information changes with great frequency and may be completely outdated by the time you read this. * Menu: * Debugging Options:: Dumping traffic to stderr or a buffer. * Transport Layer:: Media of interprocess communication. * Message Types:: What interpreters can say to each other. * State Transitions:: The message stream grammar. * Protocol:: Current EPL protocol (*subject to change*).  File: epl.info, Node: Debugging Options, Next: Transport Layer, Up: Internals Debugging Options ================= You can make either or both processes log the messages sent between them. - Perl Variable: $Emacs::EPL::debugging When this variable holds a true value, the Perl side of EPL logs messages to and from Emacs. Possible values are: `"stderr"' Send debugging output to `STDERR'. This works only when Perl is the parent process. a string Append debugging output to the file named by the string. a scalar reference Append debugging output to the scalar. This requires the IO::Scalar module. a filehandle Print debugging output to the handle. - Perl Function: Emacs::EPL::debug string... This is the function used internally to send debugging output to the destination specified by `$Emacs::EPL::debugging'. - Variable: epl-debugging When this variable's value is non-`nil', the Emacs side of EPL logs messages to and from Perl. If it is the symbol `stderr', the output goes to the standard error stream. Otherwise, it goes to a buffer named `*epl-debug*'. The log messages include the exact text sent to Perl, but the replies are printed as Lisp forms using `prin1'. However, EPL always uses a buffer named `*perl*' to receive text from Perl. Normally, it erases this buffer after every message, but when `epl-debugging' is true, it does not. - Function: epl-debug &rest objects This is the function used internally to send output to the location specified by `epl-debugging'.  File: epl.info, Node: Transport Layer, Next: Message Types, Prev: Debugging Options, Up: Internals Transport Layer ===============  File: epl.info, Node: Message Types, Next: State Transitions, Prev: Transport Layer, Up: Internals Message Types =============  File: epl.info, Node: State Transitions, Next: Protocol, Prev: Message Types, Up: Internals State Transitions =================  File: epl.info, Node: Protocol, Prev: State Transitions, Up: Internals Protocol ========  File: epl.info, Node: Copying Conditions, Next: Index, Prev: Internals, Up: Top Copying Conditions ****************** You are welcome to distribute EPL under the terms of either the Perl Artistic License (as distributed with Perl 5.6.0) or the GNU General Public License. This library is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this library; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. You may distribute copies of this documentation in accordance with the *Note GNU Free Documentation License::, Version 1.1 or any later version published by the Free Software Foundation; with no required Invariant Sections, Front-Cover texts, or Back-Cover Texts. * Menu: * GNU Free Documentation License:: The GNU FDL.  File: epl.info, Node: GNU Free Documentation License, Up: Copying Conditions GNU Free Documentation License ============================== Version 1.1, March 2000 Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other written document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference. 1. 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Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.  File: epl.info, Node: Index, Prev: Copying Conditions, Up: Top Index ***** * Menu: * $Emacs::EPL::debugging: Debugging Options. * connection types: Transport Layer. * debugging EPL: Debugging Options. * dumping message traffic: Debugging Options. * Emacs::EPL::debug: Debugging Options. * epl-debug: Debugging Options. * epl-debugging: Debugging Options. * FDL, GNU Free Documentation License: GNU Free Documentation License. * Internals: Internals. * interprocess communication: Transport Layer. * IPC: Transport Layer. * Message Types: Message Types. * messages: Internals. * perl-call: Ordinary Functions. * perl-eval: Evaluation. * perl-eval-raw: Evaluation. * pipe between Emacs and Perl: Transport Layer. * protocol: Internals. * protocol states: State Transitions. * standard error stream: Debugging Options. * state diagram: State Transitions. * State Transitions: State Transitions. * stderr: Debugging Options. * Transport Layer: Transport Layer. * wire protocol: Protocol.  Tag Table: Node: Top798 Node: Preface2864 Node: Introduction4645 Node: Perl Example5600 Node: History7831 Node: Emacs Lisp9018 Node: Coding Conventions9856 Node: Features9978 Node: Data Conversion10757 Node: Scalars12539 Node: The Null Value13601 Node: Symbols and Globrefs14078 Node: Lists and Arrayrefs14393 Node: Vectors14988 Node: Conses15257 Node: Scalar References15862 Node: Code References16004 Node: Hash Tables16147 Node: Blessed References16445 Node: Emacs Types16591 Node: Functions16703 Node: Evaluation17081 Node: Ordinary Functions18070 Node: Pass-by-Reference18546 Node: Commands21312 Node: Control Structures21408 Node: Input/Output21546 Node: Caveats21670 Node: References Incur Overhead21898 Node: Conversion Is Imperfect22049 Node: Configuration22196 Node: Installation22570 Node: The Easy Way22677 Node: Starting a Perl Process in Emacs22825 Node: Starting an Emacs Process in Perl23034 Node: Internals23224 Node: Debugging Options24124 Node: Transport Layer25789 Node: Message Types25928 Node: State Transitions26063 Node: Protocol26199 Node: Copying Conditions26295 Node: GNU Free Documentation License27655 Node: Index47518  End Tag Table