Difference between revisions of "Coding Gotchas"
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== Gotchas == | == Gotchas == | ||
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=== LJ::Entry->new always returns an LJ::Entry (DW) === | === LJ::Entry->new always returns an LJ::Entry (DW) === | ||
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=== You can modify ... === | === You can modify ... === | ||
| + | <source lang="perl"> | ||
| + | use strict; | ||
| + | |||
| + | my $x; | ||
| + | |||
| + | print "x is '$x'\n"; | ||
| + | foo($x); | ||
| + | print "x is now '$x'\n"; | ||
| + | |||
| + | sub foo { $_[0] = "bar"; } | ||
| + | </source> | ||
| + | |||
| + | Returns | ||
| + | |||
| + | <source> | ||
| + | x is '' | ||
| + | x is now 'bar' | ||
| + | </source> | ||
=== use strict + my $foo if === | === use strict + my $foo if === | ||
Revision as of 20:45, 8 March 2011
This page has a list of random weird Perl and DW gotchas
Contents
Gotchas
LJ::Entry->new always returns an LJ::Entry (DW)
my $entry = LJ::Entry->new( $u, ditemid => $deleted_ditemid ); print "Entry 1 is defined\n" if defined $entry; print "Entry 1 is valid\n" if defined $entry->valid; $entry = LJ::Entry->new( $u, ditemid => $valid_ditemid ); print "Entry 2 is defined\n" if defined $entry; print "Entry 2 is valid\n" if defined $entry->valid;
Returns
Invalid language.
You need to specify a language like this: <source lang="html4strict">...</source>
Supported languages for syntax highlighting:
4cs, 6502acme, 6502kickass, 6502tasm, 68000devpac, abap, actionscript, actionscript3, ada, algol68, apache, applescript, apt_sources, arm, asm, asp, asymptote, autoconf, autohotkey, autoit, avisynth, awk, bascomavr, bash, basic4gl, bf, bibtex, blitzbasic, bnf, boo, c, c_loadrunner, c_mac, caddcl, cadlisp, cfdg, cfm, chaiscript, cil, clojure, cmake, cobol, coffeescript, cpp, cpp-qt, csharp, css, cuesheet, d, dcl, dcpu16, dcs, delphi, diff, div, dos, dot, e, ecmascript, eiffel, email, epc, erlang, euphoria, f1, falcon, fo, fortran, freebasic, freeswitch, fsharp, gambas, gdb, genero, genie, gettext, glsl, gml, gnuplot, go, groovy, gwbasic, haskell, haxe, hicest, hq9plus, html4strict, html5, icon, idl, ini, inno, intercal, io, j, java, java5, javascript, jquery, kixtart, klonec, klonecpp, latex, lb, ldif, lisp, llvm, locobasic, logtalk, lolcode, lotusformulas, lotusscript, lscript, lsl2, lua, m68k, magiksf, make, mapbasic, matlab, mirc, mmix, modula2, modula3, mpasm, mxml, mysql, nagios, netrexx, newlisp, nsis, oberon2, objc, objeck, ocaml, ocaml-brief, octave, oobas, oorexx, oracle11, oracle8, oxygene, oz, parasail, parigp, pascal, pcre, per, perl, perl6, pf, php, php-brief, pic16, pike, pixelbender, pli, plsql, postgresql, povray, powerbuilder, powershell, proftpd, progress, prolog, properties, providex, purebasic, pycon, pys60, python, q, qbasic, rails, rebol, reg, rexx, robots, rpmspec, rsplus, ruby, s2, sas, scala, scheme, scilab, sdlbasic, smalltalk, smarty, spark, sparql, sql, stonescript, systemverilog, tcl, teraterm, text, thinbasic, tsql, typoscript, unicon, upc, urbi, uscript, vala, vb, vbnet, vedit, verilog, vhdl, vim, visualfoxpro, visualprolog, whitespace, whois, winbatch, xbasic, xml, xorg_conf, xpp, yaml, z80, zxbasic
Entry 1 is defined Entry 2 is defined Entry 2 is valid
You can modify ...
use strict; my $x; print "x is '$x'\n"; foo($x); print "x is now '$x'\n"; sub foo { $_[0] = "bar"; }
Returns
Invalid language.
You need to specify a language like this: <source lang="html4strict">...</source>
Supported languages for syntax highlighting:
4cs, 6502acme, 6502kickass, 6502tasm, 68000devpac, abap, actionscript, actionscript3, ada, algol68, apache, applescript, apt_sources, arm, asm, asp, asymptote, autoconf, autohotkey, autoit, avisynth, awk, bascomavr, bash, basic4gl, bf, bibtex, blitzbasic, bnf, boo, c, c_loadrunner, c_mac, caddcl, cadlisp, cfdg, cfm, chaiscript, cil, clojure, cmake, cobol, coffeescript, cpp, cpp-qt, csharp, css, cuesheet, d, dcl, dcpu16, dcs, delphi, diff, div, dos, dot, e, ecmascript, eiffel, email, epc, erlang, euphoria, f1, falcon, fo, fortran, freebasic, freeswitch, fsharp, gambas, gdb, genero, genie, gettext, glsl, gml, gnuplot, go, groovy, gwbasic, haskell, haxe, hicest, hq9plus, html4strict, html5, icon, idl, ini, inno, intercal, io, j, java, java5, javascript, jquery, kixtart, klonec, klonecpp, latex, lb, ldif, lisp, llvm, locobasic, logtalk, lolcode, lotusformulas, lotusscript, lscript, lsl2, lua, m68k, magiksf, make, mapbasic, matlab, mirc, mmix, modula2, modula3, mpasm, mxml, mysql, nagios, netrexx, newlisp, nsis, oberon2, objc, objeck, ocaml, ocaml-brief, octave, oobas, oorexx, oracle11, oracle8, oxygene, oz, parasail, parigp, pascal, pcre, per, perl, perl6, pf, php, php-brief, pic16, pike, pixelbender, pli, plsql, postgresql, povray, powerbuilder, powershell, proftpd, progress, prolog, properties, providex, purebasic, pycon, pys60, python, q, qbasic, rails, rebol, reg, rexx, robots, rpmspec, rsplus, ruby, s2, sas, scala, scheme, scilab, sdlbasic, smalltalk, smarty, spark, sparql, sql, stonescript, systemverilog, tcl, teraterm, text, thinbasic, tsql, typoscript, unicon, upc, urbi, uscript, vala, vb, vbnet, vedit, verilog, vhdl, vim, visualfoxpro, visualprolog, whitespace, whois, winbatch, xbasic, xml, xorg_conf, xpp, yaml, z80, zxbasic
x is '' x is now 'bar'
use strict + my $foo if
use strict; my $x = -1 if 0; # intentional false, for example. $x = 1; # This accesses a *global, persistant across requests* $x
The condition can be anything, and this bug only happens if the "my $x" line does not execute because of the condition, if the condition is true then it will end up using the local as expected.
strict does not complain about this.
Do the following instead:
use strict; my $x; $x = -1 if 0; $x = 1;
