It’d be nice to have even something like the isset() function PHP has… or add a function to the core list API to the extent of .has_key(). Dictionaries have a .has_key()…

if 'min' in element.attributes and element.attributes['min']:

Where I’m running into problems is with getting XML attributes. I’m using minidom to parse XML files. Each XML element is represented by a Python object. The XML attributes are in a map where the attribute name is the key. I want to know if an element has a certain attribute: it might, but it doesn’t have to. For example if a value is stated in the manuscript it goes in the content of the XML tag, but if the value is uncertain the tag has min and max attributes.

So this code would throw an exception if the element doesn’t have a min attribute:


if element.attributes['min']:
#do something with the value of min


I can use

if len(element.attributes) == 0:

to see if it has no attributes, but what if it has some attributes but not the ones I’m interested in?

I wouldn’t be surprised if there was an easier way to do this that I don’t know about, but so far the exception thing is working.

Also, under what circumstances are you running into this problem? Usually this kind of thing only comes up when meta-programming.