Add support to multiple property pairs in sprint (JuliaLang#39381)

* Add support to multiple property pairs in sprint

Sometimes it is required to pass multiple properties to `IOContext` in
`sprint`. For example, if we want to print with `:compact` and `:limit`
set to true. Currently, the only possible way to do this is creating an
`IOContext` using a dummy `IOBuffer` with those parameters. Hence, this
commit allows to pass a vector of pairs `:key=>value` to `context`
keyword of `sprint` so that we can easily set multiple properties.

This is not a breaking change, and no performance regression was
identified when using the previous function signatures.

* Add compat annotation to sprint

* Update base/strings/io.jl

Co-authored-by: Rafael Fourquet <[email protected]>

* Update sprint docstring

* Update NEWS.md

* Move NEWS.md entry to the correct place

Co-authored-by: Rafael Fourquet <[email protected]>

Author: 2 people

NEWS.md

@@ -38,6 +38,7 @@ New library functions
 New library features
 --------------------
 
+* The optional keyword argument `context` of `sprint` can now be set to a tuple of `:key => value` pairs to specify multiple attributes. ([#39381])
 
 Standard library changes
 ------------------------

base/strings/io.jl

@@ -79,14 +79,19 @@ println(io::IO, xs...) = print(io, xs..., "\n")
 
 Call the given function with an I/O stream and the supplied extra arguments.
 Everything written to this I/O stream is returned as a string.
-`context` can be either an [`IOContext`](@ref) whose properties will be used,
-or a `Pair` specifying a property and its value. `sizehint` suggests the capacity
-of the buffer (in bytes).
+`context` can be an [`IOContext`](@ref) whose properties will be used, a `Pair`
+specifying a property and its value, or a tuple of `Pair` specifying multiple
+properties and their values. `sizehint` suggests the capacity of the buffer (in
+bytes).
 
-The optional keyword argument `context` can be set to `:key=>value` pair
-or an `IO` or [`IOContext`](@ref) object whose attributes are used for the I/O
-stream passed to `f`.  The optional `sizehint` is a suggested size (in bytes)
-to allocate for the buffer used to write the string.
+The optional keyword argument `context` can be set to a `:key=>value` pair, a
+tuple of `:key=>value` pairs, or an `IO` or [`IOContext`](@ref) object whose
+attributes are used for the I/O stream passed to `f`.  The optional `sizehint`
+is a suggested size (in bytes) to allocate for the buffer used to write the
+string.
+
+!!! compat "Julia 1.7"
+    Passing a tuple to keyword `context` requires Julia 1.7 or later.
 
 # Examples
 ```jldoctest
@@ -99,7 +104,9 @@ julia> sprint(showerror, BoundsError([1], 100))
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
     s = IOBuffer(sizehint=sizehint)
-    if context !== nothing
+    if context isa Tuple
+        f(IOContext(s, context...), args...)
+    elseif context !== nothing
         f(IOContext(s, context), args...)
     else
         f(s, args...)

test/strings/io.jl

@@ -187,6 +187,38 @@ join(myio, "", "", 1)
     @test_throws ArgumentError unescape_string(IOBuffer(), string('\\',"N"))
     @test_throws ArgumentError unescape_string(IOBuffer(), string('\\',"m"))
 end
+
+@testset "sprint with context" begin
+    function f(io::IO)
+        println(io, "compact => ", get(io, :compact, false))
+        println(io, "limit   => ", get(io, :limit,   false))
+    end
+
+    str = sprint(f)
+    @test str == """
+        compact => false
+        limit   => false
+        """
+
+    str = sprint(f, context = :compact => true)
+    @test str == """
+        compact => true
+        limit   => false
+        """
+
+    str = sprint(f, context = (:compact => true, :limit => true))
+    @test str == """
+        compact => true
+        limit   => true
+        """
+
+    str = sprint(f, context = IOContext(stdout, :compact => true, :limit => true))
+    @test str == """
+        compact => true
+        limit   => true
+        """
+end
+
 @testset "#11659" begin
     # The indentation code was not correctly counting tab stops
     @test Base.indentation("      \t") == (8, true)