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The two standard methods are SlotSequence, and the "injector pattern." Related question on StackOverflow: How to Block Symbols without evaluating them? … {x_} :> x) myBlock[{a, b, c, d}] {1, 2, 3, 4} Injector pattern ClearAll[myBlock] SetAttributes[myBlock, HoldAll] varList = {"a", "b", "c", "d"}; myBlock[args_] := (MapIndexed[Set, Join @@ MakeExpression …

step and injector pattern First method, load my step function and use the injector pattern: z2 := {{a, {1, 2, 3}}, {b, Complement[{1, 2, 3}, {a}]}, {c, Complement[{1, 2, 3}, {a, b}]}} …

Nested injector pattern The essence of nested injector pattern is that sometimes we need to inject more than one different piece of code in a single go. … But a simple injector pattern does not allow it. The nested injector pattern allows one to accumulate several such expressions by using nested rules. …

Injector pattern: list = {1, 2, 3}; MakeExpression["list"] /. …

This could be another case for the injector pattern: var = Hold@{x = 2, y = 3, z = 4} var /. Hold[inj_] :> Block[inj, x*y*z] (*24*) ?x (*Global`x --- so we did not leak*) …

I know I can do this using Block wrapped around the call to f and g but I was curious if some cunning extension of UpValues would work; more like a dependency injector pattern. … My experience of using UpValues is very limited and reading the documentation for UpValues it would appear to be appropriate only when the precise pattern of h within f or g is known. …

Hold[code_] :> Compile @@ Hold[{y}, code] which is, using injector pattern. …

Here is my version using injector pattern: ClearAll[myWith]; SetAttributes[myWith,HoldAll]; myWith[pars_=vals_,body_]:= Apply[Set,Hold[Evaluate[Transpose[{pars,vals}]]],{2}]/. …

Here are few alternatives, using what I think I've seen called an injector pattern (which I just found in this answer by @Mr.Wizard and might be considered a duplicate): $condition = True; If[$condition …

/3 - 1/4 + 1/5 - 1/6 One may simplify this method using the undocumented function RuleCondition as WReach shows: Replace[hf, x_ :> RuleCondition[x], {2}] 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 #2 Injector … pattern: {1, -(1/2), 1/3, -(1/4), 1/5, -(1/6)} /. …

While Kuba's answer is simpler, what you asked for can be accomplished also rather easily with the help of the nested injector pattern: variables /. … {vars__} :> (Map[Pattern[#, Blank[]] &, {vars}] /. {patts__} :> (f[{patts}, x_] := g[vars, x])) …

Can it be solved with the injector pattern or the Trott-Strzebonski in-place evaluation? …

To check b against a pattern based on a, I switch out a collection of heads inject new patterns and condition the pattern on the switched out heads: myPatternPatternA=(a/. … pattern I construct, in the new pattern {f,x,y,g,h} can all take arbitrary values since I'm injecting a new pattern for them after removing {HoldPattern,Pattern,Blank,RuleDelayed}. …

Injector pattern to the rescue: Range@3 /. i_Integer :> (a[[i]] Sin[#] &) Replace[Range@3, i_ :> (a[[i]] Sin[#] &), 1] Table[j /. i_ :> (a[[i]] Sin[#] &), {j, 3}] Or using \[Function] and Array: …

Here is another alternative, in which the values of the variables are temporarily cleared using Block and an injector pattern. …