ErrorLevel should not be treated as Boolean

[john_c]

Some examples in documentation treats ErrorLevel as boolean. This is not correct.

For example, here: https://www.autohotkey.com/docs/commands/FileReadLine.htm

Code: Select all

if ErrorLevel

whereas it should be

Code: Select all

if ErrorLevel != 0

[boiler]

It is correct to be treated as Boolean because it's either 0 (False) indicating no error or 1 or 2 (truthy, meaning evaluated as True in a Boolean context) indicating an error. I use if ErrorLevel (or usually if !ErrorLevel) almost every day. For example, I (and a lot of people) use if !ErrorLevel after ImageSearch to indicate an image was found.

[swagfag]

if it quacks like a boolean... something something

[john_c]

@boiler Yes, I understand that if I need to check whether ErrorLevel is OK or not, I can treat it as Boolean.

But actually, it can contain a lot of different values, they are not limited to 1 and 0. Hence, it doesn't look really correct to treat it in such a way.

Maybe I overthink it.

[gregster]

But actually, it can contain a lot of different values, they are not limited to 1 and 0. Hence, it doesn't look really correct to treat in such a way.

Well, actually that seems pretty consistent with the general handling of boolean values in AHK (and similar to a number of other programming languages, btw):

Boolean values: When an expression is required to evaluate to true or false (such as an IF-statement), a blank or zero result is considered false and all other results are considered true. For example, the statement if ItemCount would be false only if ItemCount is blank or 0. Similarly, the expression if not ItemCount would yield the opposite result.