Perl Breaking out of an If statement

Question

This one just came up: How do I break out of an if statement? I have a long if statement, but there is one situation where I can break out of it early on.

In a loop I can do this:

while (something ) {     last if $some_condition;     blah, blah, blah     ... } 

However, can I do the same with an if statement?

if ( some_condition ) {     blah, blah, blah     last if $some_other_condition; # No need to continue...     blah, blah, blah     ... } 

I know I could put the if statement inside a block, and then I can break out of the block:

{     if ( some_condition ) {         ...         last if $some_other_condition; # No need to continue...         blah, blah, blah         ...     } } 

Or, I can create a subroutine (which is probably better programmatically):

if ( some_condition ) {     run_subroutine(); }  sub run_subroutine {     blah, blah, blah     return if $some_other_condition;     blah, blah, blah     ... } 

But is there any way to exit an if condition?

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Resolution

The question came up because I was helping someone with their code. Inside a fairly long if statement, there were several other if statements embedded in it. The code looked something like this:

 if ( $condition1 ) {     blah, blah, blah;     if ( not $condition2 ) {        blah, blah, blah;        if ( not $condition3 ) {           blah, blah, blah;        }     } } 

I thought the whole thing could be made more readable by doing this:

if ( $condition1 ) {     last if $condition2;     blah, blah, blah;     last if $condition3;     blah, blah, blah; } 

This shows that the normal flow of the if statement is standard, but under certain conditions, the if statement was exited early -- much like using last or next in a while or for loop to exit the loop.

I liked mpapec's solution of using a label -- even if I don't use the label itself. The label is a description of my if:

IF-UNDER-CONDITION1: {     if ( $condition1 ) {         last if $condition2;         blah, blah, blah;         last if $condition3;         blah, blah, blah;     } } 

Although it isn't a standard coding technique, the flow of the code is obvious enough that a typical low-level Perl developer (the one that has to maintain this code after I leave) could figure out what the code is doing and maintain it. They may even learn something in the process.

Answer 1

You can use basic block which is subject to last, next and redo, so there is possible break from it.

if ($condition) {EXIT_IF:{     last EXIT_IF; # break from code block     print "never get's executed\n"; }} 

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EXIT_IF: {   if ($condition) {       last EXIT_IF; # break from code block       print "never get's executed\n";   } } 

Answer 2

• Put it inside an empty for() loop, and add last; everywhere you want to break out AND after the if. A bit ugly but works. Make sure to add comments to explain the trick.

  for (;;) {     if (condition) {          #code         last if another_condition;     }     last; } 

• use goto and label a statement after your loop for that goto. Be forever damned.

• Extra block inside the if (e.g. if () {{ code }}). May be hard to read for novices but OK if accompanied by a comment.

• your own solution: block around if. Not very obvious readability-wise.

• your own solution: subroutine with return.

  Frankly, unless the cost of calling a sub matters performane wise, this is the cleanest solution as far as readability.