Fix error message because of macro

src/api.jl

@@ -73,7 +73,7 @@ Initializes the Optimizer library. This must be called before any other library
 
 """
 function init()
-    @checked Lib.XPRSinit(C_NULL)
+    Lib.XPRSinit(C_NULL)
 end
 
 """
@@ -83,7 +83,7 @@ Frees any allocated  memory and closes all open files.
 
 """
 function free()
-    @checked Lib.XPRSfree()
+    Lib.XPRSfree()
 end
 
 """
@@ -125,7 +125,7 @@ You can use this function to disable some of the checking and validation of func
 
 """
 function setcheckedmode(checked_mode)
-    @checked Lib.XPRSsetcheckedmode(checked_mode)
+    Lib.XPRSsetcheckedmode(checked_mode)
 end
 
 """
@@ -135,19 +135,19 @@ You can use this function to interrogate whether checking and validation of all
 
 """
 function getcheckedmode(r_checked_mode)
-    @checked Lib.XPRSgetcheckedmode(r_checked_mode)
+    Lib.XPRSgetcheckedmode(r_checked_mode)
 end
 
 function license(lic, path)
     r = Lib.XPRSlicense(lic, path)
 end
 
 function beginlicensing(r_dontAlreadyHaveLicense)
-    @checked Lib.XPRSbeginlicensing(r_dontAlreadyHaveLicense)
+    Lib.XPRSbeginlicensing(r_dontAlreadyHaveLicense)
 end
 
 function endlicensing()
-    @checked Lib.XPRSendlicensing()
+    Lib.XPRSendlicensing()
 end
 
 """
@@ -162,11 +162,12 @@ Retrieves an error message describing the last licensing error, if any occurred.
 
 """
 function getlicerrmsg(; len = 1024)
-    msg = Cstring(pointer(Array{Cchar}(undef, len*8)))
-    Lib.XPRSgetlicerrmsg(msg, len)
-    # TODO - @ checked version does not work
-    # @checked Lib.XPRSgetlicerrmsg(msg, len)
-    return unsafe_string(msg)
+    buffer = Array{Cchar}(undef, len*8)
+    buffer_p = pointer(buffer)
+    GC.@preserve buffer begin
+        Lib.XPRSgetlicerrmsg(msg, len)
+        return unsafe_string(msg)
+    end
 end
 
 """
@@ -2788,7 +2789,13 @@ Returns the error message corresponding to the last error encountered by a libra
 """
 function getlasterror(prob::XpressProblem)
     @invoke Lib.XPRSgetlasterror(prob, _)::String
-end
+    buffer = Array{Cchar}(undef, 512)
+    buffer_p = pointer(buffer)
+    GC.@preserve buffer begin
+        s = Lib.XPRSgetlasterror(prob, buffer_p)
+        return s == 0 ? unsafe_string(buffer_p) : "Unable to get last error"
+    end
+ end
 
 """
     int XPRS_CC XPRSbasiscondition(XPRSprob prob, double *condnum, double *scondnum);

src/helper.jl

@@ -62,6 +62,10 @@ mutable struct XpressProblem <: CWrapper
     end
 end
 
+function get_xpress_error_message(prob::XpressProblem)
+    lstrip(Xpress.getlasterror(prob), ['?'])
+end
+
 function XpressProblem(; logfile = "")
     ref = Ref{Lib.XPRSprob}()
     createprob(ref)

src/license.jl

@@ -74,8 +74,11 @@ function userlic(; verbose::Bool = true, liccheck::Function = emptyliccheck, xpa
     lic = liccheck(lic)
 
     # Send GIVEN LIC to XPRESS lib
-    slicmsg = Cstring(pointer(Array{Cchar}(undef, 1024*8)))
-    ierr = license(lic, slicmsg)
+    buffer = Array{Cchar}(undef, 1024*8)
+    buffer_p = pointer(buffer)
+    ierr = GC.@preserve buffer begin
+        license(lic, Cstring(buffer_p))
+    end
 
     # check LIC TYPE
     if ierr == 16

src/utils.jl

@@ -19,13 +19,15 @@ function invoke(f::Function, pos::Int, ::Type{Int}, args...)
 end
 
 function invoke(f::Function, pos::Int, ::Type{String}, args...)
-    out = Cstring(pointer(Array{Cchar}(undef, 1024)))
-
-    args = collect(Any, args)
-    insert!(args, pos-1, out)
-
-    r = f(args...)
-    r != 0 ? throw(XpressError(r, "Unable to invoke $f")) : unsafe_string(out)
+    buffer = Array{Cchar}(undef, 1024)
+    buffer_p = pointer(buffer)
+    GC.@preserve buffer begin
+        out = Cstring(buffer_p)
+        args = collect(Any, args)
+        insert!(args, pos-1, out)
+        r = f(args...)
+        return r != 0 ? throw(XpressError(r, "Unable to invoke $f")) : unsafe_string(out)
+    end
 end
 
 """
@@ -88,15 +90,50 @@ macro invoke(expr)
     return f
 end
 
+function get_xpress_error_message(xprs_ptr)
+    "(Unable to extract error message for $(typeof(xprs_ptr)).)"
+end
+
+"""
+    @checked f(prob)
+
+Lets you invoke a lower level `Lib` function and check that Xpress does not error.
+Use this macro to minimize repetition and increase readability.
+
+The first argument must be a object that can be cast into an Xpress pointer, e.g. `Ptr{XpressProblem}`.
+This is passed to `get_xpress_error_message(xprs_ptr)` to get the error message.
 
+Examples:
+
+    @checked Lib.XPRSsetprobname(prob, name)
+
+As an example of what @checked expands to:
+
+```
+julia> @macroexpand @checked Lib.XPRSsetprobname(prob, name)
+quote
+    r = Lib.XPRSsetprobname(prob, name)
+    if r != 0
+        xprs_ptr = prob
+        e = get_xpress_error_message(xprs_ptr)
+        throw(XpressError(r, "Unable to call `Xpress.setprobname`:\n\n\$(e).\n"))
+    else
+        nothing
+    end
+end
+```
+
+"""
 macro checked(expr)
     @assert expr.head == :call "Can only use @checked on function calls"
     @assert ( expr.args[1].head == :(.) ) && ( expr.args[1].args[1] == :Lib) "Can only use @checked on Lib.\$function"
+    @assert length(expr.args) >= 2 "Lib.\$function must be contain atleast one argument and the first argument must be of type XpressProblem"
     f = replace(String(expr.args[1].args[2].value), "XPRS" => "")
     return esc(quote
         r = $(expr)
         if r != 0
-            e = lstrip(Xpress.getlasterror(prob), ['?'])
+            xprs_ptr = $(expr.args[2])
+            e = get_xpress_error_message(xprs_ptr)
             throw(XpressError(r, "Unable to call `Xpress.$($f)`:\n\n$e.\n"))
         else
             nothing

test/runtests.jl

@@ -16,4 +16,6 @@ end
     @test Xpress.getcontrol(prob, "HEURTHREADS") == 0
     @test Xpress.getcontrol(prob, :HEURTHREADS) == 0
 
+    msg = "Unable to call `Xpress.copyprob`:\n\n91 Error: No problem has been input.\n"
+    @test_throws Xpress.XpressError(32,msg) Xpress.copyprob(prob, prob)
 end