From 87e45fcc6add84c7f86df7c7464f9a8a4b297b94 Mon Sep 17 00:00:00 2001
From: JamesWrigley <james@puiterwijk.org>
Date: Sat, 8 Jun 2024 18:58:54 +0200
Subject: [PATCH] Implement `lib_version()`

This is a slightly nicer API than looking up the undocumented (and mutable)
`ZMQ.version`, though `ZMQ.version` is left as a const global for backwards
compatibility.
---
 docs/src/_changelog.md |  5 +++++
 docs/src/reference.md  |  8 ++++++++
 src/ZMQ.jl             | 16 +++++++++++++---
 test/runtests.jl       |  4 ++++
 4 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/docs/src/_changelog.md b/docs/src/_changelog.md
index 5ac219f..1baff64 100644
--- a/docs/src/_changelog.md
+++ b/docs/src/_changelog.md
@@ -7,6 +7,11 @@ CurrentModule = ZMQ
 This documents notable changes in ZMQ.jl. The format is based on [Keep a
 Changelog](https://keepachangelog.com).
 
+## Unreleased
+
+### Added
+
+- [`lib_version()`](@ref) to get the libzmq version ([#240]).
 
 ## [v1.2.5] - 2024-05-28
 
diff --git a/docs/src/reference.md b/docs/src/reference.md
index a654da5..daf8aac 100644
--- a/docs/src/reference.md
+++ b/docs/src/reference.md
@@ -1,5 +1,13 @@
+```@meta
+CurrentModule = ZMQ
+```
+
 # Reference
 
+```@docs
+lib_version
+```
+
 ## Sockets
 
 The ZMQ Socket type:
diff --git a/src/ZMQ.jl b/src/ZMQ.jl
index 3bf8118..8805754 100644
--- a/src/ZMQ.jl
+++ b/src/ZMQ.jl
@@ -29,13 +29,23 @@ include("sockopts.jl")
 include("message.jl")
 include("comm.jl")
 
-function __init__()
+"""
+    lib_version()
+
+Get the libzmq version number.
+"""
+function lib_version()
     major = Ref{Cint}()
     minor = Ref{Cint}()
     patch = Ref{Cint}()
     ccall((:zmq_version, libzmq), Cvoid, (Ptr{Cint}, Ptr{Cint}, Ptr{Cint}), major, minor, patch)
-    global version = VersionNumber(major[], minor[], patch[])
-    if version < v"3"
+    return VersionNumber(major[], minor[], patch[])
+end
+
+const version = lib_version()
+
+function __init__()
+    if lib_version() < v"3"
         error("ZMQ version $version < 3 is not supported")
     end
     atexit() do
diff --git a/test/runtests.jl b/test/runtests.jl
index cc79f7d..8668cfa 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -164,6 +164,10 @@ end
     @test !isopen(leaked_ctx)
 end
 
+@testset "Utilities" begin
+    @test ZMQ.lib_version() isa VersionNumber
+end
+
 @testset "Aqua.jl" begin
     Aqua.test_all(ZMQ)
 end