variables exist

[Fredrik Lundh]

"fabian" wrote:

> how testing if a variable exists in python as isset in php??

try:
    variable
except NameError:
    print "variable not set"

but that is really lousy Python; better make sure you always assign to
all variables, and use None (or another suitable value) to mark that some
variable has no meaningful content right now.

that is, instead of

    if condition:
        variable = 1

    ...

    try:
        variable
    except NameError:
        ....

write

    variable = None

    if condition:
        variable = 1

    ...

    if variable is None:
        print "variable not set"

</F>