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It can be useful to manage test data across multiple functions with Rules:
testRules1 = {a$0 -> 1.0, b$0 -> 2.0, c$0 -> 3.0, d$0 -> 4.0, n$0 -> 2}
{a$0 -> 1., b$0 -> 2., c$0 -> 3., d$0 -> 4., n$0 -> 2}
testRules2 = {a$0 -> 1.1, b$0 -> 2.2, c$0 -> 3.3, d$0 -> 4.4, n$0 -> 3}
{a$0 -> 1.1, b$0 -> 2.2, c$0 -> 3.3, d$0 -> 4.4, n$0 -> 3}
Note how this employs the Webel convention of suffixing a variable name with '$0' to indicate that it is an "initialisation" target!
Note also how the functions the test data are applied to need not use every variable:
fSimple[a_, b_] := a + b;
fSimple[a$0, b$0] /. testRules1
3.
fSimple[a$0, b$0] /. testRules2
3.3
By having the test data as rule sets they can be used with other functions with a different number of arguments and/or different order (which is far more robust for testing):
fDifferentOrder[b_, a_, c_] := a - b * c;
fDifferentOrder[b$0, a$0, c$0] /. testRules1
-5.
However, one can't always sensibly apply the rules AFTER the function "acts" on its arguments:
fWithLoop[n_Integer, a_, b_] := Module[
{out = {}},
For[i = 1, i <= n, i++, AppendTo[out, fSimple[a, b]^i]];
out
];
The following won't loop, it does not yet know 'n$0' before the rules are applied:
fWithLoop[n$0, a$0, b$0] /. testRules1
{}
So use an "arguments helper" to capture the rules first then use Apply
(or @@
):
args$fWithLoop[rules_] := {n$0, a$0, b$0} /. rules;
fWithLoop @@ args$fWithLoop[testRules1]
{3., 9.}
Consider this looping function wrapper with Options
:
Options[fWithLoopAndOption] = {doDouble -> False};
fWithLoopAndOption[n_Integer, a_, b_, OptionsPattern[]] := Module[
{out = fWithLoop[n, a, b]},
If[OptionValue[doDouble], 2 # & /@ out, out]
];
{fWithLoopAndOption[2, 1.0, 2.0],fWithLoopAndOption[2, 1.0, 2.0, doDouble -> True]}
{{3., 9.},{6., 18.}}
A quite general args handler can be defined. There is no need to define the actual Options
for the arguments handler, just accept an OptionsPattern[]
:
args$any[argNames_,rules_, opt : OptionsPattern[]] :=
Join[argNames /. rules, {opt}];
args$any[{n$0, a$0, b$0}, testRules1, doDouble -> False]
{2, 1., 2., doDouble -> False}
fWithLoopAndOption @@
args$any[{n$0, a$0, b$0}, testRules1, doDouble -> False]
{3., 9.}
fWithLoopAndOption @@
args$any[{n$0, a$0, b$0}, testRules1, doDouble -> True]
{6., 18.}