CODEWITHSUNDEEP
pythonpython-2.7
J. Stacky
J. Stacky

Reputation: 27

Python use string value as class / part of code

is it possible to use a value of a string directly inside of the code as a class etc? I don't know to exactly describe what I want to do with words, so the pseudo code version is probably the best way to understand what's the issue. Here is the example:

for node in itemdict.iterkeys():
    nodeinfo = itemdict.get(node)

    if nodeinfo[4] == "node": #create new Links based on original nodeclass
        #Example if nodeinfo[1] == "Dot"
        #link = nuke.nodes.Dot(hide_input=nodeinfo[3], label='to: ' + nodeinfo[2])
        link = nuke.nodes.XXX_value of nodeinfo[1] here_XX(hide_input=nodeinfo[3], label='to: ' + nodeinfo[2])

Upvotes: 0

Views: 100

Answers (2)

snakecharmerb
snakecharmerb

Reputation: 55630

You want to use the getattr builtin function to get attributes from objects by name:

for node in itemdict.iterkeys():
    nodeinfo = itemdict.get(node)

    if nodeinfo[4] == "node": #create new Links based on original nodeclass
        # Get the attribute named <the value of nodeinfo[1]> from nuke.nodes
        cls = getattr(nuke.nodes, nodeinfo[1])
        link = cls(hide_input=nodeinfo[3], label='to: ' + nodeinfo[2])

If the object does not have an attribute wit the name that you passed to getattr, an AttributeError will be raised. You can either handle this error in your code or pass a third argument to getattr, which getattr will return instead raising AttributeError.

Upvotes: 1

blhsing
blhsing

Reputation: 106543

If you want to get a class by name, you can use the built-in function globals to obtain it.

For example:

class A(object):
    def __init__(self):
        self.number = 1

class B(object):
    def __init__(self):
        self.number = 2

for name in 'A', 'B':
    print(globals()[name]().number)

This outputs:

1
2

Upvotes: 1

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