Re^3: return if 0

in reply to Re^2: return if 0
in thread return if 0

To be fair, it wouldn't be insane for the compiler to know that the block can never execute, and just remove it completely.

Except for the part that it has unexpected consequences, as we've been discussing.

-- zigdon

Comment on Re^3: return if 0

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Re^4: return if 0 by ikegami (Patriarch) on Jun 23, 2009 at 01:02 UTC
It does remove the `if`, but it keeps the constant to maintain the behaviour. `>perl -MO=Concise,-exec,f -e"sub f { return 1 if 0 }" main::f: 1 <;> nextstate(main 1 -e:1) v 2 <$> const[IV 0] s/SHORT 3 <1> leavesub[1 ref] K/REFC,1 -e syntax OK` [download] Compared to: `>perl -MO=Concise,-exec,f -e"sub f { return 1 if $c }" main::f: 1 <;> nextstate(main 1 -e:1) v 2 <#> gvsv[*c] s 3 <\|> and(other->4) K/1 4 <0> pushmark s 5 <$> const[IV 1] s 6 <@> return K 7 <1> leavesub[1 ref] K/REFC,1 -e syntax OK` [download] Note the `and` operator (used to implement `if`) is missing from the first snippet.	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^4: return if 0
by ikegami (Patriarch) on Jun 23, 2009 at 01:02 UTC

if

>perl -MO=Concise,-exec,f -e"sub f { return 1 if 0 }"
main::f:
1  <;> nextstate(main 1 -e:1) v
2  <$> const[IV 0] s/SHORT
3  <1> leavesub[1 ref] K/REFC,1
-e syntax OK
[download]

Compared to:

>perl -MO=Concise,-exec,f -e"sub f { return 1 if $c }"
main::f:
1  <;> nextstate(main 1 -e:1) v
2  <#> gvsv[*c] s
3  <|> and(other->4) K/1
4      <0> pushmark s
5      <$> const[IV 1] s
6      <@> return K
7  <1> leavesub[1 ref] K/REFC,1
-e syntax OK
[download]

Note the and operator (used to implement if) is missing from the first snippet.

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