What is a Python equivalent of PHP’s var_dump()

PROBLEM:

• When debugging in PHP, we frequently find it useful to simply stick a var_dump() in our code to show me what a variable is, what its value is, and the same for anything that it contains.
• What is a good Python equivalent for this?

When debugging in PHP, we frequently find it useful to simply stick a var_dump() in our code to show me what a variable is, what its value is, and the same for anything that it contains.

SOLUTION 1:

• To display a value, you can use the pprint module. The easiest way to dump all variables with it is to do

[pastacode lang=”python” manual=”import%20pprint%0A%0Apprint.pprint(globals())%0Apprint.pprint(locals())%0A” message=”python code” highlight=”” provider=”manual”/] [ad type=”banner”]

• If you are running in CGI, a useful debugging feature is the cgitb module, which displays the value of local variables as part of the traceback.

SOLUTION 2:

[pastacode lang=”python” manual=”def%20dump(obj)%3A%0A%20%20”’return%20a%20printable%20representation%20of%20an%20object%20for%20debugging”’%0A%20%20newobj%3Dobj%0A%20%20if%20’__dict__’%20in%20dir(obj)%3A%0A%20%20%20%20newobj%3Dobj.__dict__%0A%20%20%20%20if%20’%20object%20at%20’%20in%20str(obj)%20and%20not%20newobj.has_key(‘__type__’)%3A%0A%20%20%20%20%20%20newobj%5B’__type__’%5D%3Dstr(obj)%0A%20%20%20%20for%20attr%20in%20newobj%3A%0A%20%20%20%20%20%20newobj%5Battr%5D%3Ddump(newobj%5Battr%5D)%0A%20%20return%20newobj%0A” message=”Python code” highlight=”” provider=”manual”/]

• Here is the usage

[pastacode lang=”python” manual=”class%20stdClass(object)%3A%20pass%0Aobj%3DstdClass()%0Aobj.int%3D1%0Aobj.tup%3D(1%2C2%2C3%2C4)%0Aobj.dict%3D%7B’a’%3A1%2C’b’%3A2%2C%20’c’%3A3%2C%20’more’%3A%7B’z’%3A26%2C’y’%3A25%7D%7D%0Aobj.list%3D%5B1%2C2%2C3%2C’a’%2C’b’%2C’c’%2C%5B1%2C2%2C3%2C4%5D%5D%0Aobj.subObj%3DstdClass()%0Aobj.subObj.value%3D’foobar’%0Afrom%20pprint%20import%20pprint%0Apprint(dump(obj))%0A” message=”Python code” highlight=”” provider=”manual”/]

and the results

[pastacode lang=”python” manual=”%7B%0A’__type__’%3A%20’%3C__main__.stdClass%20object%20at%200x2b126000b890%3E’%2C%0A%20’dict’%3A%20%7B’a’%3A%201%2C%20’c’%3A%203%2C%20’b’%3A%202%2C%20’more’%3A%20%7B’y’%3A%2025%2C%20’z’%3A%2026%7D%7D%2C%0A%20’int’%3A%201%2C%0A%20’list’%3A%20%5B1%2C%202%2C%203%2C%20’a’%2C%20’b’%2C%20’c’%2C%20%5B1%2C%202%2C%203%2C%204%5D%5D%2C%0A%20’subObj’%3A%20%7B’__type__’%3A%20’%3C__main__.stdClass%20object%20at%200x2b126000b8d0%3E’%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20’value’%3A%20’foobar’%7D%2C%0A%20’tup’%3A%20(1%2C%202%2C%203%2C%204)%0A%7D%0A” message=”Python code” highlight=”” provider=”manual”/] [ad type=”banner”]

SOLUTION 3:

• You can simply install it using pip:

[pastacode lang=”python” manual=”pip%20install%20var_dump%0A” message=”Python code” highlight=”” provider=”manual”/]

SOLUTION 4:

• Here we use self-written Printer class, but dir() is also good for outputting the instance fields/values.

class Printer:

[pastacode lang=”python” manual=”%20%20%20%20%20%20%20def%20__init__%20(self%2C%20PrintableClass)%3A%0A%20%20%20%20%20%20%20%20%20%20%20for%20name%20in%20dir(PrintableClass)%3A%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20value%20%3D%20getattr(PrintableClass%2Cname)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20if%20%20’_’%20not%20in%20str(name).join(str(value))%3A%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20print%20’%20%20.%25s%3A%20%25r’%20%25%20(name%2C%20value)%0A” message=”Python code” highlight=”” provider=”manual”/]

• The sample of usage:

[pastacode lang=”python” manual=”Printer(MyClass)%0A” message=”Python code” highlight=”” provider=”manual”/]

SOLUTION 5:

• In PHP’s var_dump() is pprint() with the getmembers() function in the built-in inspect module:

[pastacode lang=”python” manual=”from%20inspect%20import%20getmembers%0Afrom%20pprint%20import%20pprint%0Apprint(getmembers(yourObj))%0A” message=”python code” highlight=”” provider=”manual”/]

SOLUTION 6:

• The best equivalent to PHP’s var_dump($foo, $bar) is combine print with vars:

[pastacode lang=”python” manual=”print%20vars(foo)%2Cvars(bar)%0A” message=”python code” highlight=”” provider=”manual”/] [ad type=”banner”]