use gnustep objective-c

first app

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{
    NSAutoreleasePool *pool = [NSAutoreleasePool new];
    NSLog(@"first start");
    [pool drain];
    
    return 0;
}

tech

1. 专注于概念，而不是迷失在语言技术细节中
2. 编程语言的目的是成为一个更好的程序员; 也就是说，在设计和实现新系统以及维护旧系统方面变得更加有效

the basic structure of objc program has

1. header preprocess
2. interface
3. implementation
4. method
5. variable
6. declare and expression
7. comment

use interface and implementation

#import <Foundation/Foundation.h>

@interface SampleClass:NSObject
- (void)sampleMethod;
@end

@implementation SampleClass
- (void)sampleMethod
{
    NSLog(@"hello from sample class");
}
@end

int main()
{
    SampleClass *sampleClass = [[SampleClass alloc]init];
    [sampleClass sampleMethod];

    return 0;
}

type system

1. basic integer set and float set
2. enum type
3. void type
4. derive type include pointer, array, struct, union, function

// so far we still use Foundation
int main()
{
    NSLog(@"type int takes %d\n",sizeof(int));
    NSLog(@"Storage size for float : %d , maxval=%f \n", sizeof(float), FLT_MAX);
    int c_i = 1;
    NSInteger i = 1;
    NSLog(@"%d\n",i);
}

support c type variable and c type function

void test()
{
    printf("this is c type function\n");
}

#define DEBUG YES
const int G_error_no = 1;// notice that upper case of const is a good style 
int main()
{  
    test();// cosume the c type function
    NSLog(@"err no: %d\n",G_error_no);
}

基本运算符(算术，逻辑,位运算)的支持是和c保持一致，这里比较简单

1. https://www.yiibai.com/objective_c/objective_c_operators.html#article-start

method in objc

• (return_type) method_name:( argumentType1 )argumentName1
  joiningArgument2:( argumentType2 )argumentName2 …
  joiningArgumentn:( argumentTypen )argumentNamen {
  body of the function
  }

// skip the class declare and impl
// notice that java style is good style
// and joiningArgument just needed to take its place,but not a real name of argument
-(int)max:(int)num1 secondNumber:(int)num2{
    if (num1 > num2)return num1;
    else return num2;
}

int main(){
    // call the method,for example using a class
    SampleClass *sampleClass = [[SampleClass alloc]init];
    int ret = 
        [sampleClass max:1 secondNumber:2];
    printf("%d\n",ret);
}
// 函数参数按值传参和按引用/指针传参是支持的，有机会在深入一遍c语言

block is an instance (error with enable blocks using -fblocks)[notfix]

仅表示单个任务或行为单元而不是方法集合是有意义的(using block),它允许创建不同的代码段，这些代码段可以传递给方法或函数，就像它们是值一样。 块是Objective-C对象，因此它们可以添加到NSArray或NSDictionary等集合中。 它们还能够从封闭范围中捕获值，使其类似于其他编程语言中的闭包或lambda

returntype (^blockName)(argumentType);

returntype (^blockName)(argumentType)= ^{
};

use application.make

#filename must:GNUmakefile
GNUSTEP_MAKEFILES = /usr/share/GNUstep/Makefiles
SRC_DIR = . #this dir is source code directory
include ${GNUSTEP_MAKEFILES}/common.make
APP_NAME = main #name of application
main_OBJC_FILES = $(SRC_DIR)/main.m # a main.m file, if add .m file just add behind, we should have header as well
main_RESOURCE_FILES = # yet I dont know how to use
include ${GNUSTEP_MAKEFILES}/application.make
include ${GNUSTEP_MAKEFILES}/tool.make
include ${GNUSTEP_MAKEFILES}/Master/tool.make
# GNUstep reference may be in `linux mint`: /usr/share/GNUstep/Documentation

1. then run make in the makefile folder

code reference

• the above link

Todos

1. read the rest post an get this file done