comparison mercurial/extensions.py @ 29765:19578bb84731

extensions: add unwrapfunction to undo wrapfunction

Before this patch, we don't have a safe way to undo a wrapfunction because
other extensions may wrap the same function and calling setattr will undo
them accidentally.

This patch adds an "unwrapfunction" to address the issue. It removes the
wrapper from the wrapper chain, and re-wraps everything, which is not the
most efficient but short and easy to understand. We can revisit the code
if we have perf issues with long chains.

The "undo" feature is useful in cases like wrapping a function just in a
scope. Like, having a "select" command to interactively (using arrow keys)
select content from some output (ex. smartlog). It could wrap "ui.label" to
extract interesting texts just in the "select" command.

29764:8bf97c4c6c2a

    assert callable(origfn)
    wrap = bind(wrapper, origfn)
    _updatewrapper(wrap, origfn, wrapper)
    setattr(container, funcname, wrap)
    return origfn

def getwrapperchain(container, funcname):
    '''get a chain of wrappers of a function

    Return a list of functions: [newest wrapper, ..., oldest wrapper, origfunc]

29765:19578bb84731

    assert callable(origfn)
    wrap = bind(wrapper, origfn)
    _updatewrapper(wrap, origfn, wrapper)
    setattr(container, funcname, wrap)
    return origfn

def unwrapfunction(container, funcname, wrapper=None):
    '''undo wrapfunction

    If wrappers is None, undo the last wrap. Otherwise removes the wrapper
    from the chain of wrappers.

    Return the removed wrapper.
    Raise IndexError if wrapper is None and nothing to unwrap; ValueError if
    wrapper is not None but is not found in the wrapper chain.
    '''
    chain = getwrapperchain(container, funcname)
    origfn = chain.pop()
    if wrapper is None:
        wrapper = chain[0]
    chain.remove(wrapper)
    setattr(container, funcname, origfn)
    for w in reversed(chain):
        wrapfunction(container, funcname, w)
    return wrapper

def getwrapperchain(container, funcname):
    '''get a chain of wrappers of a function

    Return a list of functions: [newest wrapper, ..., oldest wrapper, origfunc]