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Oh, I didn't realize that had a name! My boss does that, and it is incredibly irritating.

Not in this case, but Yoda conditions can be useful. The most common case is preventing accidental assignment when you are trying to check for the equality of values.

Say that you mean to do:

    if (something == 2)

If you forget an equal sign, the resulting code can lead to subtile bugs:

    if (something = 2) // Not what we meant

If you are using a Yoda condition and forget an equal sign, you'll get an error right away (so that you can correct it):

    if (2 = something) // Error

There are other use cases, particularly related to nil values, but this should show you the gist of it.

> Not in this case, but Yoda conditions can be useful.

Not in Python. Assignments as anything but stand-alone (potentially chained) statements are syntax errors.

The parser will not let you write

    if something = 2:

in the first place.

That's why I said "not in this case". There are languages affected by this though (typically C-based ones). Ideally, their compiler will give you a warning about it, but that's not always the case.

May be irritating for some but good practice regardless.

Putting the constant left in a conditional means you will never miss an accidental = instead of ==.

> Putting the constant left in a conditional means you will never miss an accidental = instead of ==.

That's only useful for dumb languages

    >>> a = 5
    >>> if a = 3: print 'ok'; else: print 'nok'
      File "<stdin>", line 1
        if a = 3: print 'ok'; else: print 'nok'
             ^
    SyntaxError: invalid syntax

Python simply does not allow assignments in conditional contexts.

Dumb is a strong word, young padawan.

The difference between theory and practice is smaller in theory than in practice.

> Dumb is a strong word, young padawan.

I carefully weighted my words, and I rest my case.

> That's only useful for dumb languages

The compilers/interpreters I know that don't do this are PHP and Perl (C/C++ will do it if you use -Wall, which you should be using anyway).

So yeah, you're pretty much right. /snark

Perl does indeed warn about the use of = instead of == in a conditional.

You're right; I didn't know about the -w setting. I guess that just leaves PHP.

That's like wearing a helmet while walking down the street because you might accidentally fall and hit your head.

Don't be an idiot in the first place and you won't have to do idiotic things to prevent damage from your idiocy.

    Good judgement is the result of experience.
    Experience is the result of bad judgement.  <-- You are here

Until you're system is crippled by a bug as a result of not using them.

This is something that cannot happen in Python. Yoda conditions are entirely pointless in that language.

A good programmer looks both ways before crossing a one-way street.

A better programmer uses -Wall and lets the compiler check for him.

Confidence, n.: The feeling you have before you understand the situation

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