added struct dict example

Author: Pyrolistical

allocate.py

@@ -3,8 +3,8 @@
 cffi = FFI()
 cffi.cdef(
     """
-      char* allocByteArrayZ(long long size);
-      void printZ(char* messageZ);
+      char* allocByteArrayZ(unsigned long long size);
+      void printZ(char* message);
       void freeByteArrayZ(char* array);
       bool detectLeaks();
     """
@@ -14,11 +14,11 @@
 
 allocate = cffi.dlopen(os.path.abspath("allocate.dll"))
 
-messageZ = allocate.allocByteArrayZ(5)
-messageZ[0:5] = b"hello"
+message = allocate.allocByteArrayZ(5)
+message[0:5] = b"hello"
 
-allocate.printZ(messageZ)
+allocate.printZ(message)
 
-allocate.freeByteArrayZ(messageZ)
+allocate.freeByteArrayZ(message)
 
 print("leaked: {leaked}".format(leaked=allocate.detectLeaks()))

hello-world.py

@@ -9,7 +9,7 @@
 
 import os
 
-helloWorld = cffi.dlopen(os.path.abspath("hello-world.dll"))
+hello_world = cffi.dlopen(os.path.abspath("hello-world.dll"))
 
 # pass in null-terminated array
-helloWorld.printZ(b"Hello world\x00")
+hello_world.printZ(b"Hello world\x00")

struct-dict.py

@@ -0,0 +1,55 @@
+from cffi import FFI
+
+cffi = FFI()
+cffi.cdef(
+    """
+      typedef struct {
+        bool boolean;
+        char byte;
+        char array[6];
+        char* stringZ;
+      } SomeStruct;
+
+      SomeStruct getStruct();
+      void setStruct(SomeStruct some_struct);
+    """
+)
+
+import os
+
+struct_dict = cffi.dlopen(os.path.abspath("struct-dict.dll"))
+
+
+def toDict(struct):
+    return dict(
+        boolean=struct.boolean,
+        byte=struct.byte[0],
+        array=list(cffi.buffer(struct.array)[:]),
+        stringZ=cffi.string(struct.stringZ).decode("utf-8"),
+    )
+
+
+print(toDict(struct_dict.getStruct()))
+
+
+def toStruct(some_dict):
+    some_struct = cffi.new("SomeStruct *")
+    some_struct.boolean = some_dict["boolean"]
+    some_struct.byte = some_dict["byte"].to_bytes(length=1, byteorder="big")
+    some_struct.array = cffi.from_buffer("char[6]", bytearray(some_dict["array"]))
+    some_struct.stringZ = cffi.from_buffer(
+        "char[]", some_dict["stringZ"].encode("utf-8")
+    )
+    return some_struct[0]
+
+
+struct_dict.setStruct(
+    toStruct(
+        dict(
+            boolean=True,
+            byte=42,
+            array=[5, 4, 3, 2, 1, 0],
+            stringZ="hello from python",
+        )
+    )
+)

struct-dict.zig

@@ -0,0 +1,22 @@
+const std = @import("std");
+
+const SomeStruct = extern struct {
+    boolean: bool,
+    byte: u8,
+    array: [6]u8,
+    stringZ: [*:0]const u8,
+};
+
+export fn getStruct() callconv(.C) SomeStruct {
+    return .{
+        .boolean = true,
+        .byte = 42,
+        .array = .{ 5, 4, 3, 2, 1, 0 },
+        .stringZ = "hello from zig",
+    };
+}
+
+export fn setStruct(some_struct: SomeStruct) callconv(.C) void {
+    std.debug.print("{}\n", .{some_struct});
+    std.debug.print("{s}\n", .{some_struct.stringZ});
+}