Add support for transformed_value inside fields

Closes #43

Author: disberd

CHANGELOG.md

@@ -10,6 +10,7 @@ This file contains the changelog for the PlutoExtras package. It follows the [Ke
 
 ### Added
 - Added possibility of providing any valid object with a `MIME"text/html"` representation as description of the `@NTBond` macro.
+- Added the possibility of simplifying application of `PlutoUI.Experimental.transformed_value` to the fields of an `@NTBond` using the `@tv` decorator (see the example notebook for details).
 
 ### Changed
 - Changed the hiding behavior of the `Popout` container so that it stays displayed if the mouse is hovering over its contents even if not popped out

src/structbond/macro.jl

@@ -1,4 +1,49 @@
 # Helper Functions #
+##### Functions copied from MacroTools.jl ####
+walk(x, inner, outer) = outer(x)
+walk(x::Expr, inner, outer) = outer(Expr(x.head, map(inner, x.args)...))
+prewalk(f, x)  = walk(f(x), x -> prewalk(f, x), identity)
+##### End of MacroTools.jl functions ####
+
+# This traverse the expression and eventually replaces all single underscores with the provided alternative value
+function replace_single_underscore(ex::Expr, newval::Symbol)
+    changed = Ref(false)
+    newex = prewalk(ex) do x
+        if x === :_
+            changed[] = true
+            return newval
+        else
+            return x
+        end
+    end
+    return newex, changed[]
+end
+
+# This will take an expression and check if it contains single underscores identifiers. If it does, it assumes it has to translate this into an anonymous function with a single argument that will go in place of the underscore
+make_function(x) = x
+function make_function(ex::Expr)
+    Meta.isexpr(ex, :(->)) && return ex
+    newsym = gensym()
+    newex, changed = replace_single_underscore(ex, newsym)
+    if changed
+        return Expr(:(->), newsym, Expr(:block, newex))
+    else
+        return ex
+    end
+end
+
+# This function will try parsing the fieldbond expression to eventually deal with `@tv`
+process_fieldbond_expression(x) = x
+function process_fieldbond_expression(ex::Expr)
+    Meta.isexpr(ex, :macrocall) || return ex
+    args = filter(x -> !(x isa LineNumberNode), ex.args)
+    macro_name = args[1]
+    macro_name == Symbol("@tv") || return ex
+    length(args) == 3 || throw(ArgumentError("The @tv decorator has to be called with two arguments after it.\nThe first must be the transforming function and the second the widget"))
+    _, func, widget = args
+    return :($(transformed_value)($(make_function(func)), $widget))
+end
+
 # Generic function for the convenience macros to add methods for the field functions
 function _add_generic_field(s, block, fnames)
 	if !Meta.isexpr(block, [:block, :let])
@@ -18,6 +63,9 @@ function _add_generic_field(s, block, fnames)
 		# If the value is not already a tuple or vect or expressions, we wrap it in a tuple
 		values = Meta.isexpr(value, [:vect, :tuple]) ? value.args : (value,)
 		for (fname,val) in zip(reverse(fnames), reverse(values))
+            if fname == :fieldbond
+                val = process_fieldbond_expression(val)
+            end
 			# Push the expression to overload the method
 			push!(out.args, esc(:($Mod.$fname(::Type{$s}, ::Val{$symbol}) = $val)))
 		end
@@ -332,7 +380,7 @@ end
 
 function _NTBond(desc, block, tv)
     expr = _NTBond(desc, block)
-    return :($(transformed_value)($(esc(tv)), $expr))
+    return :($(transformed_value)($(esc(make_function(tv))), $expr))
 end
 
 

test/notebooks/structbondmodule.jl

@@ -151,11 +151,35 @@ md"""
 @bind transformed_value_example @NTBond md"Transformed!" begin
 	a = Slider(1:10)
 	b = Slider(1:10)
-end nt -> nt.a + nt.b
+end _.a + _.b # This function is replaced within the macro to be `nt -> nt.a + nt.b`, which could have also been provided as anonymous function directly
 
 # ╔═╡ 1d5573ee-872e-4dfb-a785-1ac9e836ad98
 transformed_value_example
 
+# ╔═╡ 5bb22f07-fbea-44ab-9783-9ca16e0da11e
+md"""
+### Transform only a few fields
+"""
+
+# ╔═╡ 134d6033-2f08-4f49-9829-6a023b368a70
+md"""
+A similar approach can also be achieved on a field by field basis by using the `@tv` decorator (which is not a macro per-se but is directly processed during the macro expansion of `@NTBond`).
+
+`@tv` is a shorthand for transformed_value and it expects two arguments after it, the first being the function to process the value returned by the widget, and the second being the widget itself.
+
+This can be used to be a bit less verbose when one is interested in only transforming one of many fields as below:
+"""
+
+# ╔═╡ 02e58012-5af6-4b91-a9a4-09c9dc038f11
+@bind transform_single_field @NTBond "Field Level Transformed Value" begin
+	a = ("Angle [°]", @tv deg2rad Slider(0:90; default = 60, show_value=true)) # This transforms the angle into radians
+	b = Slider(1:10)
+	c = Slider(1:10)
+end
+
+# ╔═╡ e102613f-244c-4b49-9837-535bf047a14a
+transform_single_field
+
 # ╔═╡ 8eb18c7f-bb4d-4cdc-9e30-d561f9099800
 md"""
 ## Markdown math in description
@@ -166,11 +190,14 @@ md"""
 The description of an `@NTBond` can now be provided as anything that has a valid `MIME"text/html"` representation. This includes markdown with math inside!
 """
 
+# ╔═╡ bb04ac12-20a0-467a-af1a-c298301e4838
+markdown_function = nt -> atan(nt.x, nt.y) + 3
+
 # ╔═╡ 36faf18c-11c3-4012-a996-55c7cdae71a8
 math_ntbond = @bind atanval @NTBond md"This is math!: ``\;atan(x,y) + 3``" begin
-	x = (md"``x``", Slider(1:10))
-	y = (md"``y``", Slider(1:10))
-end nt -> atan(nt.x, nt.y) + 3
+	x = (md"``x``", Slider(1:10; show_value=true))
+	y = (md"``y``", Slider(1:10; show_value=true))
+end markdown_function # We can also directly use functions in the caller scope to transform the value
 
 # ╔═╡ 27977526-75dc-44c3-9976-c22e8cbd94da
 atanval
@@ -570,8 +597,13 @@ version = "17.5.0+2"
 # ╟─4cb128aa-7ad8-4d17-bced-36845703e6a8
 # ╠═7855826e-ccaa-4c27-a060-f5ceb927bbe8
 # ╠═1d5573ee-872e-4dfb-a785-1ac9e836ad98
+# ╟─5bb22f07-fbea-44ab-9783-9ca16e0da11e
+# ╟─134d6033-2f08-4f49-9829-6a023b368a70
+# ╠═02e58012-5af6-4b91-a9a4-09c9dc038f11
+# ╠═e102613f-244c-4b49-9837-535bf047a14a
 # ╟─8eb18c7f-bb4d-4cdc-9e30-d561f9099800
 # ╟─052b8bbd-acca-4c00-a5de-0c717ed068e3
+# ╠═bb04ac12-20a0-467a-af1a-c298301e4838
 # ╠═36faf18c-11c3-4012-a996-55c7cdae71a8
 # ╠═27977526-75dc-44c3-9976-c22e8cbd94da
 # ╟─da3ae348-083d-4a7d-aabd-d0bc25b3ca17