Re: A performance issue when using default value

On 2月1日, 下午1时20分, alex23 wrote: > alex23 wrote: > > keakon wrote: > > > def h2(x=[]): > > > y = x > > > y.append(1) > > > return y + [] > > > Are you aware that 'y = x' _doesn't_ make a copy of [], that it > > actu

A performance issue when using default value

I've found strange performance issue when using default value, the test code is list below: from timeit import Timer def f(x): y = x y.append(1) return y def g(x=[]): y = [] y.append(1) return y def h(x=[]): y = x y.append(1) return y def f2(x): y = x y.append(1) return