On 14/08/2013 18:21, Alexey Mishustin wrote:
If I make a typo and write a single "equals" operator here:
if ($foo = 2) {
print "yes\n";
}
...then the "warnings" pragma works OK and tells me "Found = in
conditional, should be ==..."
But if I make the same typo and write a single "equals" operator there:
if ($foo = $bar) {
print "yes\n";
}
... then I get no warning; the script output is "yes".
Why is it so?
How could I catch such typos?
The `warnings` pragma catches the first form because the value of the
conditional is a *constant* 2, so the body of the `if` will *always* be
executed and it is a fair guess that the problem is `=` instaed of `==`.
In the second case the execution depends on the value of `$bar`, and it
is a reasonable thing to write if, say, you wanted to test a value and
assign it to a temporary variable at the same time. Perl cannot know
that the code was unintentional and will not warn you.
I have checked both Perl::Critic and B::Lint, and neither of these check
for an assignment operator in a conditional expression. The only thing
way I can think of doing this is to write a plugin for B::Lint, which
accepts Module::Pluggable plugins. It may be possible to write something
that will do what you want.
Rob
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