Re^2: Treating file lines in a text file as a string

I'll be damned. This reminds me of a story.

In about 2002 when I'd been hacking Perl quite a bit for 3 years I started to feel like I wanted to know how far I'd come. I was self-taught and pretty uneasy about my skills even though I'd accomplished some large projects, even an international one, at a large company. I looked around online till I found some Perl self-tests. There were three tests: beginner, moderate, expert. Feeling sheepish, I thought I'd better do the beginner first to get a good score and then move on. I expected to ace it.

I got like a 55% or something. I was so mad I blazed through the expert exam. Got 100% to my amazement. Being self-taught on real projects I knew references and objects and that sort of jazz pretty well, but I couldn't even answer some of the basics because they'd never come up.

In 9 years of Perl hacking, I did not know till now that there was a readline function in Perl or that there was anything else underlying the diamond operator.

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Re^3: Treating file lines in a text file as a string by ikegami (Patriarch) on May 22, 2008 at 09:05 UTC
`readline` are `<>` are two names for the same op (`readline`). `>perl -MO=Concise -e"<FH>" 5 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 1 -e:1) v ->3 4 <1> readline[t2] vK/1 ->5 3 <#> gv[FH] s ->4 -e syntax OK >perl -MO=Concise -e"readline(FH)" 6 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 1 -e:1) v ->3 5 <1> readline[t2] vK/1 ->6 4 <1> rv2gv sKR/1 ->5 3 <#> gv[*FH] s ->4 -e syntax OK` [download] Similarly, ``, qx`` and `readpipe` are three names for the same op (`backtick`). `and` and `&&` are the same op, and `or` and `\|\|` are the same op. Finally, `if` and `unless` are implemented using the `and` and `or` ops respectively.	[reply] [d/l] [select]
Re^4: Treating file lines in a text file as a string by Burak (Chaplain) on May 22, 2008 at 12:15 UTC
"and and && are the same op, and or and \|\| are the same op." I think there is a difference (precedence) between these ops...	[reply]
Re^5: Treating file lines in a text file as a string by ikegami (Patriarch) on May 22, 2008 at 17:09 UTC
Precedence only affects parsing. The same op is used in the resulting tree for both of these operators. >perl -MO=Concise -e"$a and $b" 6 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 1 -e:1) v ->3 - <1> null vK/1 ->6 4 <\|> and(other->5) vK/1 ->6 - <1> ex-rv2sv sK/1 ->4 3 <#> gvsv[a] s ->4 - <1> ex-rv2sv vK/1 ->- 5 <#> gvsv[b] s ->6 -e syntax OK >perl -MO=Concise -e"$a && $b" 6 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 1 -e:1) v ->3 - <1> null vK/1 ->6 4 <\|> and(other->5) vK/1 ->6 - <1> ex-rv2sv sK/1 ->4 3 <#> gvsv[a] s ->4 - <1> ex-rv2sv vK/1 ->- 5 <#> gvsv[b] s ->6 -e syntax OK [download] And check out "`if`": `>perl -MO=Concise -e"if ($a) { $b }" 6 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 3 -e:1) v ->3 - <1> null vK/1 ->6 4 <\|> and(other->5) vK/1 ->6 - <1> ex-rv2sv sK/1 ->4 3 <#> gvsv[a] s ->4 - <@> scope vK ->- \ The only difference - <0> ex-nextstate v ->5 / is the extra scope. - <1> ex-rv2sv vK/1 ->- 5 <#> gvsv[b] s ->6` [download]	[reply] [d/l] [select]