Python's equivalent for define
I have this code in ruby:
class Package
def initialize(name)
@name = name
@elements = []
end
[:type, :block].each do |bindtype|
define_method "get_#{bindtype}_by_name" do |name|
get_by_name(name, bindtype)
end
end
def get_by_name(name, bindtype=nil)
@elements.each do |element|
return if element.name == name
end
return nil
end
I've read this question about define_method in python and I wanted to implement the same thing in Python with my Ruby code:
bindtypes = {"type", "block"}
class Package:
def __init__(self, name):
self.name = name
self.elements = list()
def get_by_name(self, name, bindtype=None):
for element in self.elements:
if element.name == name:
return element
return None
for bindtype in bindtypes:
def _in_bindtype(self, bindtype, bindtype):
Package.get_by_name(bindtype, bindtype)
setattr(Package, "get_"+bindtype+"_by_name", _in_bindtype
I call the function like this:
package = Package("package")
block = Block("blockName")
package.elements.append(block)
blockFound = package.get_block_by_name(block.name, block.bindtype)
But obviously this doesn't work because I don't recover the name of the element that I'm searching. Can someone help me understand better how this python define_method works with my code?
You were almost there; bind the bindtype
value as a default value for the function argument, and you want to call get_by_name()
on self
:
for bindtype in bindtypes:
def _in_bindtype(self, name, bindtype=bindtype):
self.get_by_name(name, bindtype)
setattr(Package, "get_{}_by_name".format(bindtype), _in_bindtype)
I took the liberty of using str.format()
to format the method name rather than use +
concatenation, it is more readable I find.
Alternatively, in Python 3 you could just create functools.partialmethod()
objects:
from functools import partialmethod
for bindtype in bindtypes:
setattr(Package, "get_{}_by_name".format(bindtype),
partialmethod(Package.get_by_name, bindtype=bindtype))
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