add docstring, Overflow check

src/log/binning.jl

@@ -214,8 +214,18 @@ function _sum_type_heuristic(::Type{T}, elndims::Integer) where T
     return S
 end
 
-function LogBinner(B::LogBinner{S, M}, capacity::Int64 = _nlvls2capacity(32)) where {S, M}
+"""
+    LogBinner(B::LogBinner[; capacity::Int])
+
+Creates a new `LogBinner` from an existing LogBinner, copying the data inside.
+The new LogBinner may be larger or smaller than the given one.
+"""
+function LogBinner(B::LogBinner{S, M}; capacity::Int64 = _nlvls2capacity(32)) where {S, M}
     N = _capacity2nlvls(capacity)
+    B.count[min(M, N)] > 0 && throw(OverflowError(
+        "The new LogBinner is too small to reconstruct the given LogBinner. " *
+        "New capacity = $capacity   Old capacity = $(B.count[min(M, N)])"
+    ))
     el = zero(B.x_sum[1])
 
     LogBinner{S, N}(

test/logbinning.jl

@@ -13,7 +13,7 @@
         @test B == B2
         @test !(B != B2)
 
-        B3 = LogBinner(B, 10_000)
+        B3 = LogBinner(B, capacity=10_000)
         @test B3 == B
         @test capacity(B3) == 16383
 
@@ -26,7 +26,8 @@
 
         @test B3 != B
         @test isempty(B3)
-        B3 = LogBinner(B, 10_000)
+        @test_throws OverflowError LogBinner(B, capacity=10)
+        B3 = LogBinner(B, capacity=10_000)
         @test B3 == B
         @test !isempty(B3)
 
@@ -53,7 +54,7 @@
         @test B == B2
         @test !(B != B2)
 
-        B3 = LogBinner(B, 10_000)
+        B3 = LogBinner(B, capacity=10_000)
         @test B3 == B
         @test capacity(B3) == 16383
 
@@ -66,7 +67,8 @@
 
         @test B3 != B
         @test isempty(B3)
-        B3 = LogBinner(B, 10_000)
+        @test_throws OverflowError LogBinner(B, capacity=10)
+        B3 = LogBinner(B, capacity=10_000)
         @test B3 == B
         @test !isempty(B3)