D language front-end merged with GCC 9; some sample D programs

By Vasudev Ram

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The D Language Front-End Merged Into GCC 9 (phoronix.com)

HN thread about it.

D is a nice language, and fast both to compile and run. It has a wide range of features, but one can get started with it without learning all of them. It's fast both to compile and to run. Dev time is fast too.

I commented on the HN thread above too, giving a list of some of my own small D language programs (mainly command-line utilities) that can serve as a quick introduction to some of the different things that you can do with D.

I've reproduced the links to those D programs for the convenience of my readers, below:

"Here are a handful of D programs that use various features of the language and some of its libraries, on my blog. Most of them are simple command-line utilities to do various things. Readers may find them of use to get a flavor of the language and to know some of the kinds of things it can be used for."

A few of the posts are about interviews with D language people too.

Don't miss the interview where the creators or key people from the C++, Rust, D and Go languages talk to each other on a panel about some of the pros and cons of their respective languages - and the incident near the end of the video, involving Bjarne Stroustrup (the LangNext video below).

Here are those D-related posts:

Porting the text pager from Python to D (DLang)

Simple parallel processing in D with std.parallelism

Video: Interview: GoingNative 6: Walter Bright and Andrei Alexandrescu - D Programming Language

Using std.datetime.StopWatch to time sections of D code

Read from CSV with D, write to PDF with Python

Command line D utility - find files matching a pattern under a directory

min_fgrep: minimal fgrep command in D

num_cores: find number of cores in your PC's processor

Calling a simple C function from D - strcmp

Component programming in D - DDJ article by Walter Bright

Func-y D + Python pipeline to generate PDF

Interview: Ruminations on D: Walter Bright, DLang creator

file_sizes utility in D: print sizes of all files under a directory tree

Video: C++, Rust, D and Go: Panel at LangNext '14

deltildefiles: D language utility to recursively delete vim backup files

[DLang]: A simple file download utility in D

Getting CPU info with D (the D language)

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- Vasudev Ram - Online Python training and consulting

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Command line D utility - find files matching a pattern under a directory

By Vasudev Ram

Hi readers,

I wrote this utility in D recently, to find files matching a pattern (a wildcard) under a specified directory. Here is the program, find_files.d:

/************************************************************************
find_files.d
Author: Vasudev Ram
Compile with Digital Mars D compiler using the command:
dmd find_files.d
Usage: find_files dir patt
Finds files under directory 'dir' that match file wildcard 
pattern 'patt'.
The usual file wildcard patterns that an OS like Windows or 
Linux supports, such as *.txt, budget*.xls, my_files*, etc.,
are supported.
Copyright 2016 Vasudev Ram
Web site: https://vasudevram.github.io
Blog: http://jugad2.blogspot.com
Product updates: https://gumroad.com/vasudevram/follow
************************************************************************/

import std.stdio; 
import std.file;

string __version__ = "0.1";

void usage(string[] args) {
    debug {
        stderr.write("You gave the command: ");
        foreach(arg; args)
            stderr.write(arg, " ");
        stderr.writeln;
    }
    
    stderr.writeln(args[0], " (Find Files) v", __version__);
    stderr.writeln("Copyright 2016 Vasudev Ram" ~
    " - https://vasudevram.github.io");
    stderr.writeln("Usage: ", args[0], " dir pattern");
    stderr.writeln("Recursively find filenames, under directory 'dir', ");
    stderr.writeln("that match the literal or wildcard string 'pattern'.");
}

int main(string[] args) {

    // Check for and get correct command-line arguments.
    if (args.length != 3) {
        usage(args);
        return 1;
    }
    auto top_dir = args[1];
    if (!exists(top_dir) || !isDir(top_dir)) {
        stderr.writeln("The name ", top_dir, 
        " does not exist or is not a directory.");
        usage(args);
        return 1;
    }
    auto pattern = args[2];

    try {
        debug writeln(args[0], ": Finding files under directory: ", 
        top_dir, " that match pattern: ", pattern);
        foreach (de; dirEntries(top_dir, pattern, SpanMode.breadth)) {
            writeln(de.name);
        }
    }
    catch (Exception e) {
        stderr.writeln("Caught Exception: msg = ", e.msg);
        return 1;
    }
    return 0;
}

Compile command:

$ dmd -offf find_files.d

The -of flag is for "output file", and is used to specify the .EXE file to be created. The command creates ff.exe on Windows).

Compile command to create debug version (the statements prefixed 'debug' will also run):

$ dmd -debug -offf find_files.d

Here is the output from a few test runs of the find_files utility:

Run with no arguments - shows usage:

$ ff
ff (Find Files) v0.1
Copyright 2016 Vasudev Ram - https://vasudevram.github.io
Usage: ff dir pattern
Recursively find filenames, under directory 'dir',
that match the literal or wildcard string 'pattern'.

Run with one argument, a non-existent directory - shows usage, since number of arguments is invalid:

$ ff z
ff (Find Files) v0.1
Copyright 2016 Vasudev Ram - https://vasudevram.github.io
Usage: ff dir pattern
Recursively find filenames, under directory 'dir',
that match the literal or wildcard string 'pattern'.

Run with two argument, a non-existent directory and a file wildcard, * - gives message that the directory does not exist, and shows usage:

$ ff z *
The name z does not exist or is not a directory.
ff (Find Files) v0.1
Copyright 2016 Vasudev Ram - https://vasudevram.github.io
Usage: ff dir pattern
Recursively find filenames, under directory 'dir',
that match the literal or wildcard string 'pattern'.

Run with two argument, an existing directory and a file wildcard, * - gives the output of the files matching the wildcard under that directory (recursively):

$ ff . *
.\dir1
.\dir1\a.txt
.\dir1\dir11
.\dir1\dir11\b.txt
.\dir2
.\dir2\c.txt
.\dir2\dir21
.\dir2\dir21\d.txt
.\ff.exe
.\ff.obj
.\ffd.exe
.\find_files.d
.\find_files.d~

Note: It will find hidden files too, i.e. those with a H attribute, as shown by the DOS command DIR /A. If you find any issue with the utility, please describe it, with the error message, in the comments.

You can get the find_files utility (as source code) from here on my Gumroad product store:

https://gum.co/find_files

Compile the find_files.d program with the Digital Mars D compiler using the command:

dmd find_files.d

whhich will create the executable file find_files.exe.

Run:

find_files

to get help on the usage of the utility. The examples above in this post have more details.

- Enjoy.

Drawing of magnifying glass at top of post, by:

Yours truly.

- Vasudev Ram - Online Python training and consulting

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