Merge pull request #11 from JuliaGraphs/ignull

introduce IGNull

Author: Krastanov

CHANGELOG.md

@@ -1,5 +1,9 @@
 # News
 
+## v0.10.17 - 2025-06-29
+
+- `IGNull` is introduced as a convenient placehold argument for when the low-level C function expects a `NULL` as a default.
+
 ## v0.10.16 - 2025-04-21
 
 - `IGVector*` and `IGMatrix*` support the corresponding julia `AbstractArray` interfaces now.

Project.toml

@@ -1,7 +1,7 @@
 name = "IGraphs"
 uuid = "647e90d3-2106-487c-adb4-c91fc07b96ea"
 authors = ["Stefan Krastanov <stefan@krastanov.org>"]
-version = "0.10.16"
+version = "0.10.17"
 
 [deps]
 CEnum = "fa961155-64e5-5f13-b03f-caf6b980ea82"

README.md

@@ -2,7 +2,7 @@ A thin Julia wrapper around the C graphs library [`igraph`](https://igraph.org/)
 
 ### Wrapper types
 
-Most C types (like `igraph_vector_int_t`) are directly available in `IGraphs.LibIGraph` and also have Julian wrappers (like `IGVectorInt`).
+Most C types (like `igraph_vector_int_t`) are directly available in `IGraphs.LibIGraph` and also have Julian wrappers (like `IGVectorInt`). There is also `IGNull` as a convenient placeholder for whenever the `igraph` C function expects a `NULL` argument.
 
 ### High-level Julian interfaces
 

src/IGraphs.jl

@@ -8,7 +8,8 @@ export LibIGraph, IGraph, IGraphException,
     IGBitSet,
     #IGraphList,
     IGVectorIntList, IGVectorFloatList, IGMatrixFloatList, IGBitSetList,
-    IGAdjList
+    IGAdjList,
+    IGNull
 
 const last_thrown_error_ref = Ref{Any}() # TODO make this thread safe
 

src/types.jl

@@ -61,3 +61,11 @@ for (ptr_ctype, jtype) in pairs(wrappedtypes)
     end
     eval(expr)
 end
+
+"""Convenient wrapper for `C_NULL` to be used when `LibIGraph` functions need a `NULL` argument."""
+struct IGNull
+    objref
+    function IGNull()
+        return new(C_NULL)
+    end
+end

test/test_assorted_api.jl

@@ -1,6 +1,7 @@
 @testitem "Assorted API checks" begin
 
 import Graphs
+using Graphs: ne, nv
 using IGraphs
 using Test
 
@@ -17,4 +18,19 @@ using Test
     @test collect(v) == [0,2,1,0,1]
 end
 
+@testset "NULL input arguments" begin
+    g = Graphs.smallgraph(:karate)
+    ig = IGraph(g)
+
+    membership = IGVectorInt(zeros(nv(ig)))
+    membership_null = IGVectorInt(zeros(nv(ig)))
+    edge_weights = IGVectorFloat(ones(ne(ig)))
+    node_weights = IGVectorFloat(ones(nv(ig)))
+
+    res = LibIGraph.community_leiden(ig, edge_weights, node_weights, 0.05, 0.01, 0, 1, membership)
+    res_null = LibIGraph.community_leiden(ig, IGNull(), IGNull(), 0.05, 0.01, 0, 1, membership_null)
+    @test membership == membership_null
+    @test res == res_null
+end
+
 end