如何解决我们应该避免使用C ++中的重复代码以使其“ Pythonic”吗？如何？
| 我处于Python的幼虫阶段，而处于C ++的预蛋阶段，但是我正在努力做到最好，尤其是遵循“不要重复自己”的原则。 我有一个要打开的多通道原始文件格式，带有一个主要的ascii标头，其字段可表示为字符串和整数（始终编码为用空格填充的字符）。第二部分是N个标头，其中N是主标头的字段，并且这些标头中的每个标头本身都有许多文本和数字字段（编码为ascii），这些字段涉及实际的16位多通道流的长度和大小。组成文件的其余部分。 到目前为止，我在C ++中有以下工作代码：#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <map>
using namespace std;
struct Header {
string version;
string patinfo;
string recinfo;
string start_date;
string start_time;
int header_bytes;
string reserved;
int nrecs;
double rec_duration;
int nchannels;
};
struct Channel {
string label;
string transducertype;
string phys_dim;
int pmin;
int pmax;
int dmin;
int dmax;
string prefiltering;
int n_samples;
string reserved;
};
int main()
{
ifstream edf(\"/home/helton/Dropbox/01MIOTEC/06APNÉIA/Samples/Osas2002plusQRS.rec\",ios::binary);
// prepare to read file header
Header header;
char buffer[80];
// reads header fields into the struct \'header\'
edf.read(buffer,8);
header.version = string(buffer,8);
edf.read(buffer,80);
header.patinfo = string(buffer,80);
edf.read(buffer,80);
header.recinfo = string(buffer,8);
header.start_date = string(buffer,8);
header.start_time = string(buffer,8);
stringstream(buffer) >> header.header_bytes;
edf.read(buffer,44);
header.reserved = string(buffer,44);
edf.read(buffer,8);
stringstream(buffer) >> header.nrecs;
edf.read(buffer,8);
stringstream(buffer) >> header.rec_duration;
edf.read(buffer,4);
stringstream(buffer) >> header.nchannels;
/*
cout << \"\'\" << header.version << \"\'\" << endl;
cout << \"\'\" << header.patinfo << \"\'\" << endl;
cout << \"\'\" << header.recinfo << \"\'\" << endl;
cout << \"\'\" << header.start_date << \"\'\" << endl;
cout << \"\'\" << header.start_time << \"\'\" << endl;
cout << \"\'\" << header.header_bytes << \"\'\" << endl;
cout << \"\'\" << header.reserved << \"\'\" << endl;
cout << \"\'\" << header.nrecs << \"\'\" << endl;
cout << \"\'\" << header.rec_duration << \"\'\" << endl;
cout << \"\'\" << header.nchannels << \"\'\" << endl;
*/
// prepare to read channel headers
int ns = header.nchannels; // ns tells how much channels I have
char title[16]; // 16 is the specified length of the \"label\" field of each channel
for (int n = 0; n < ns; n++)
{
edf >> title;
cout << title << endl; // and this successfully echoes the label of each channel
}
return 0;
};
解决方法
我会说没有Pythonic C ++代码之类的东西。 DRY原理在两种语言中都适用，但是使用Python特定的构造，大多数被认为是Python语言的最简单，最甜蜜的方式就是“ Pythonic”。惯用的C ++完全不同。
例如，有时将
lambda
map
dict
header.version = read_field(edf,8);
header.patinfo = read_field(edf,80);
template <typename TStream,typename TResult>
void ReadFixedWidthFieldFromStream(TStream& str,TResult& result,unsigned sz)
{
std::vector<char> data(sz);
if (!str.read(&data[0],sz))
throw std::runtime_error(\"Failed to read from stream\");
std::stringstream ss(&data[0]);
if (!(ss >> result))
throw std::runtime_error(\"Failed to parse data from stream\");
}
// Overload for std::string:
template <typename TStream>
void ReadFixedWidthFieldFromStream(TStream& str,std::string& result,sz))
throw std::runtime_error(\"Failed to read from stream\");
result = std::string(&data[0],sz);
}
ReadFixedWidthFieldFromStream(edf,header.version,8);
ReadFixedWidthFieldFromStream(edf,header.patinfo,80);
ReadFixedWidthFieldFromStream(edf,header.recinfo,80);
// etc.
>>> import this
The Zen of Python,by Tim Peters
Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren\'t special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity,refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you\'re Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain,it\'s a bad idea.
If the implementation is easy to explain,it may be a good idea.
Namespaces are one honking great idea -- let\'s do more of those!
struct Header {
char version[8];
char patinfo[80];
char recinfo[80];
char start_date[8];
char start_time[8];
int header_bytes;
char reserved[44];
int nrecs;
double rec_duration;
int nchannels;
};
struct Header h;
edf.read(&h,sizeof(struct Header));
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