A generic Context class to store globals and other settings w/o changing function's definition using void* pointers.
It uses C++20 but can be easily bakcported to older versions.
It is one header file and some examples.
Some mechanism for protection are implemented.
Free to use under CC0 1.0.
Next are collapsible regions.
The main() (requires v0.0.2): Used to invoke the examples.
#include "Context.hpp"
using namespace DIM;
using namespace std;
void use1(Context&, ...) {}
void use2(Context&, ...) {}
int main()
{
try
{
// include here the "Ex*.inc" files!
#include "Tests/Ex1.inc"
//Examples of calling other functions with the context.
use1(c);
use2(c, 10, 22, "a string");
}
catch (const std::exception &e)
{
cout << "\n\n" << toS(e.what(), DIM_WHERE) << "\n\n";
}
catch (const DIM::Exception &e)
{
cout << "\n\n" << toS(e.what_, e.where_) << "\n\n";
}
return 0;
}Example 1 (requires v0.0.2): Wrong Returned Type.
Context c;
I n{10};
c["i"] = makePair(n);
R r{10.12};
c["r"] = makePair(r);
S s{"Cucu"};
c["s"] = makePair(s);
cout << extract<I>(c, "i", DIM_WHERE) << '\n';
cout << extract<R>(c, "r", DIM_WHERE) << '\n';
cout << extract<S>(c, "s", DIM_WHERE) << '\n';
cout << extract<R>(c, "s", DIM_WHERE) << '\n'; // Wrong type!10
10.12
Cucu
EXCEPTION : "Key: 's' assigned to a different type.", From: "main()", file: "Ex1.inc", line: 12.
Example 2 (requires v0.0.2): Wrong Returned Type.
Context c;
I n{10};
c["i"] = makePair(n);
R r{10.12};
c["r"] = makePair(r);
S s{"Cucu"};
c["s"] = makePair(s);
cout << extract<I>(c, "i", DIM_WHERE) << '\n';
cout << extract<R>(c, "r", DIM_WHERE) << '\n';
cout << extract<S>(c, "s", DIM_WHERE) << '\n';
cout << extract<S>(c, "wrongKey", DIM_WHERE) << '\n'; // Wrong key!10
10.12
Cucu
EXCEPTION : "Key: 'wrongKey' not found in context.", From: "main()", file: "Ex2.inc", line: 12.
Example 3 (requires v0.0.5): Print context content.
Context c;
I n{10};
c["i"] = makePair(n);
R r{-22.212};
c["r"] = makePair(r);
S s{"Cucu"};
c["s"] = makePair(s);
print(c);
cout << extract<I>(c, "i", DIM_WHERE) << '\n';
cout << extract<R>(c, "r", DIM_WHERE) << '\n';
cout << extract<S>(c, "s", DIM_WHERE) << '\n';Context content:
{
i : int,
r : double,
s : class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,
}
10
-22.212
Cucu
Example 4 (requires v0.0.6): VariableHolder.
Context c;
cout << "----------------\n";
{ // using manual names for VariableHolder
VariableHolder<I> vh1(c, "i1", 10, DIM_WHERE);
VariableHolder<I> vh2(c, "i2", 15, DIM_WHERE);
cout << "Checkpoint: A";
print(c);
cout << extract<I>(c, "i1", DIM_WHERE) << '\n';
cout << extract<I>(c, "i2", DIM_WHERE) << '\n';
}
cout << "Checkpoint: B";
print(c);
cout << "----------------\n";
{ // using automatic names.VariableHolder
DIM_AUTO_VARIABLE_HOLDER(I, c, "i1", 20);
DIM_AUTO_VARIABLE_HOLDER(I, c, "i2", 25);
cout << "Checkpoint: C";
print(c);
cout << extract<I>(c, "i1", DIM_WHERE) << '\n';
cout << extract<I>(c, "i2", DIM_WHERE) << '\n';
}
cout << "Checkpoint: D";
print(c);
cout << "----------------\n";
{ // using automatic names.VariableHolder
DIM_AUTO_VARIABLE_HOLDER(I, c, "i1", 20);
DIM_AUTO_VARIABLE_HOLDER(I, c, "i2", 25);
cout << "Checkpoint: E";
print(c);
cout << extract<I>(c, "i1", DIM_WHERE) << '\n';
cout << extract<I>(c, "i2", DIM_WHERE) << '\n';
cout << "Assign them to new values.\n";
extract<I>(c, "i1", DIM_WHERE) = 21;
extract<I>(c, "i2", DIM_WHERE) = 26;
cout << "Checkpoint: F";
print(c);
cout << extract<I>(c, "i1", DIM_WHERE) << '\n';
cout << extract<I>(c, "i2", DIM_WHERE) << '\n';
}
cout << "Checkpoint: G";
print(c);
cout << "----------------\n";
cout << "Checkpoint: H";
cout << extract<I>(c, "i2", DIM_WHERE) << '\n'; // Throws!----------------
Checkpoint: A
Context content:
{
i1 : int,
i2 : int,
}
10
15
Checkpoint: B
Context content:
{
}
----------------
Checkpoint: C
Context content:
{
i1 : int,
i2 : int,
}
20
25
Checkpoint: D
Context content:
{
}
----------------
Checkpoint: E
Context content:
{
i1 : int,
i2 : int,
}
20
25
Assign them to new values.
Checkpoint: F
Context content:
{
i1 : int,
i2 : int,
}
21
26
Checkpoint: G
Context content:
{
}
----------------
Checkpoint: H
EXCEPTION : "Key: 'i2' not found in context.", From: "main()", file: "Ex4.inc", line: 49.
Example 5 (requires v0.0.7): Swap variables in a scope.
Context c;
DIM_AUTO_VARIABLE_HOLDER(I, c, "I", 10);
cout << extract<I>(c, "I", DIM_WHERE) << '\n';
{
I i{20};
DIM_AUTO_SWAP_KEY(i, c["I"].first);
cout << extract<I>(c, "I", DIM_WHERE) << '\n';
}
cout << extract<I>(c, "I", DIM_WHERE) << '\n';10
20
10
Example 6 (requires v0.0.7): Swap dynamic variables in a scope.
struct OStream
{
public:
virtual V print(const SV) = 0;
virtual ~OStream() {}
};
struct OStream1 : public OStream
{
virtual V print(const SV v) override { cout << "S1: " << v; }
};
struct OStream2 : public OStream
{
virtual V print(const SV v) override { cout << "S2: " << v; }
};
Context c;
OStream1 os1;
DIM_AUTO_VARIABLE_HOLDER(OStream &, c, "os", os1);
extract<OStream>(c, "os", DIM_WHERE).print("CUCU!\n");
{
OStream2 os2;
// DIM_AUTO_SWAP_KEY(os2, c["os"].first);//is not working yet and I will appreciate help wit it!
c["os"].first = &os2;
extract<OStream>(c, "os", DIM_WHERE).print("CUCU!\n");
c["os"].first = &os1;
}
extract<OStream>(c, "os", DIM_WHERE).print("CUCU!\n");S1: CUCU!
S2: CUCU!
S1: CUCU!