问题
In python, to dynamically load a module, you can simply use the _____import_____ statement and assign the module to a variable, I.e(from the docs):
spam = __import__('spam', globals(), locals(), [], -1)
I have used this several times in python in order to simulate dynamic module loading/unloading, because to "unload" the module, you can simply remove all references to it, I.e:
spam = None
Is there an equivalent to this in Ruby? I looked at a few other questions (this, this, and this), but I wanted to know a way to constrain a loaded module to a variable, if possible.
回答1:
Does this do what you want?
require 'bigdecimal/math' # a module from stdlib
bm = BigMath # a module is just an object
BigMath = nil # yields a warning, but BigMath is gone.
puts bm.log(10, 40).to_s # it's alter ego lives.
#=> 0.230258509299404568401799145468436420760110148862877297632502494462371208E1
回答2:
AFAIK, Ruby doesn't really have the concept of a single export object that a required file could assign to a variable; thus, I don't see how you would do this.
Note, however, that you could still use things like remove_const to undefine classes that have already been loaded.
回答3:
Nah, not possible. If you require or load a file in Ruby, you import the file into the global namespace.
来源：https://stackoverflow.com/questions/8449134/equivalent-to-pythons-dynamic-import-statement-in-ruby