Following a tip in this post, I use string parameters to label my functions. For example, instead of f[x]:=x^2, I use f["label",x_]:=x^2.
Unfortunately, this strategy breaks the default values for optional arguments, at least when the default value is a global variable.
What should happen:
f[x_,y_:var]:=x+y
var=10;
f[1]
11
var=20;
f[1]
21
What happens when using string parameters as a label:
g["label",x_,y_:var]:=x+y
var=10;
g["label",1]
11
var=20;
g["label",1]
11
It doesn't update to the new value when the global variable is changed. Why not? And more importantly, how can I fix this (without changing my nice labeling scheme, I hope)?
varandgas you're doing it, it will be obvious why the example shown exhibits the behavior you observe, and why that behavior is expected and unrelated to your "label" construct. $\endgroup$ClearAll[var]; g["label",x_,y_:var]:=x+y;. (I'd recommendClearAll[g, var].) $\endgroup$ClearAllor to re-define every function. $\endgroup$ClearAll-- you're stuck with how Mathematica works. But here's an alternative:Block[{var}, g["label", x_, y_: var] := x + y ]$\endgroup$ClearAllbetween every time I decide to change the value ofvar. In fact, I just need to use it once to clearvar, then re-define the function so thatvarremains in the function definition, and then the function responds to changes invar. $\endgroup$