From: Michael G. Schwern Date: Tue, 13 May 2003 18:33:05 +0000 (-0700) Subject: New introduction X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=6014d0cb2904bf89033c6aa0d3dbb1d1600d6994;p=p5sagit%2Fp5-mst-13.2.git New introduction Message-ID: <20030514013305.GB22001@windhund.schwern.org> p4raw-id: //depot/perl@20154 --- diff --git a/pod/perlsyn.pod b/pod/perlsyn.pod index 5ddd7e1..9aec074 100644 --- a/pod/perlsyn.pod +++ b/pod/perlsyn.pod @@ -4,23 +4,27 @@ perlsyn - Perl syntax =head1 DESCRIPTION -A Perl script consists of a sequence of declarations and statements. -The sequence of statements is executed just once, unlike in B -and B scripts, where the sequence of statements is executed -for each input line. While this means that you must explicitly -loop over the lines of your input file (or files), it also means -you have much more control over which files and which lines you look at. -(Actually, I'm lying--it is possible to do an implicit loop with -either the B<-n> or B<-p> switch. It's just not the mandatory -default like it is in B and B.) - -Perl is, for the most part, a free-form language. (The only exception -to this is format declarations, for obvious reasons.) Text from a -C<"#"> character until the end of the line is a comment, and is -ignored. If you attempt to use C C-style comments, it will be -interpreted either as division or pattern matching, depending on the -context, and C++ C comments just look like a null regular -expression or defined-or operator, so don't do that. +A Perl program consists of a sequence of declarations and statements +which run from the top to the bottom. Loops, subroutines and other +control structures allow you to jump around within the code. + +Perl is a B language, you can format and indent it however +you like. Whitespace mostly serves to separate tokens, unlike +languages like Python where it is an important part of the syntax. + +Many of Perl's syntactic elements are B. Rather than +requiring you to put parenthesis around every function call and +declare every variable, you can often leave such explicit elements off +and Perl will figure out what you meant. This is known as B, abbreviated B. It allows programmers to be B and to +code in a style which they are comfortable. + +Perl B and concepts from many languages: awk, sed, C, +Bourne Shell, Smalltalk, Lisp and even English. Other +languages have borrowed syntax from Perl, particularly its regular +expression extensions. So if you have programmed in another language +you will see familiar pieces in Perl. They often work the same, but +see L for information about how they differ. =head2 Declarations @@ -79,6 +83,12 @@ like an ordinary statement, and is elaborated within the sequence of statements as if it were an ordinary statement. That means it actually has both compile-time and run-time effects. +=head2 Comments + +Text from a C<"#"> character until the end of the line is a comment, +and is ignored. Exceptions include C<"#"> inside a string or regular +expression. + =head2 Simple Statements The only kind of simple statement is an expression evaluated for its diff --git a/pod/perltrap.pod b/pod/perltrap.pod index 6a6a443..d8f667c 100644 --- a/pod/perltrap.pod +++ b/pod/perltrap.pod @@ -18,6 +18,11 @@ Accustomed B users should take special note of the following: =item * +A Perl program executes only once, not once for each input line. You can +do an implicit loop with C<-n> or C<-p>. + +=item * + The English module, loaded via use English; @@ -174,7 +179,9 @@ Variables begin with "$", "@" or "%" in Perl. =item * -Comments begin with "#", not "/*". +Comments begin with "#", not "/*" or "//". Perl may interpret C/C++ +comments as division operators, unterminated regular expressions or +the defined-or operator. =item * @@ -206,6 +213,11 @@ Seasoned B programmers should take note of the following: =item * +A Perl program executes only once, not once for each input line. You can +do an implicit loop with C<-n> or C<-p>. + +=item * + Backreferences in substitutions use "$" rather than "\". =item *