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authorPaul Buetow <paul@buetow.org>2022-01-29 22:15:01 +0000
committerPaul Buetow <paul@buetow.org>2022-01-29 22:15:01 +0000
commit37485bba8e127be8bb3bd6e42093c0275ecccefd (patch)
tree9e36f83f009f7883fa8feef40e9fe6bcffacf40a /gemfeed
parentb5cf90ebc5d91efab7549bd0eacfcd94b0bfa4b6 (diff)
Publishing new version
Diffstat (limited to 'gemfeed')
-rw-r--r--gemfeed/2016-11-20-object-oriented-programming-with-ansi-c.gmi (renamed from gemfeed/2016-11-20-methods-in-c.gmi)39
-rw-r--r--gemfeed/atom.xml46
-rw-r--r--gemfeed/index.gmi2
3 files changed, 58 insertions, 29 deletions
diff --git a/gemfeed/2016-11-20-methods-in-c.gmi b/gemfeed/2016-11-20-object-oriented-programming-with-ansi-c.gmi
index ea2e585d..4af65381 100644
--- a/gemfeed/2016-11-20-methods-in-c.gmi
+++ b/gemfeed/2016-11-20-object-oriented-programming-with-ansi-c.gmi
@@ -1,10 +1,19 @@
-# Methods in C
+# Object oriented programming with ANSI C
-> Published by Paul at 2016-11-20
+```
+ ___ ___ ____ ____
+ / _ \ / _ \| _ \ / ___|
+| | | | | | | |_) |____| |
+| |_| | |_| | __/_____| |___
+ \___/ \___/|_| \____|
+
+```
-You can do some sort of object-oriented programming in the C Programming Language. However, that is very limited. But also very easy and straightforward to use.
+> Published by Paul at 2016-11-20, updated 2022-01-29
-## Example
+You can do a little of object-oriented programming in the C Programming Language. However, that is, in my humble opinion, limited. It's easier to use a different programming language than C for OOP. But still it's an interesting exercise to try using C for this.
+
+## Function pointers
Let's have a look at the following sample program. All you have to do is to add a function pointer such as "calculate" to the definition of struct "something_s". Later, during the struct initialization, assign a function address to that function pointer:
@@ -42,7 +51,7 @@ int main(void) {
}
```
-As you can see, you can call the function (pointed by the function pointer) the same way as in C++ or Java via:
+As you can see, you can call the function (pointed by the function pointer) with the same syntax as in C++ or Java:
```
printf("%s(%f, %f) => %f\n", mult.name, a, b, mult.calculate(a,b));
@@ -59,15 +68,15 @@ printf("%s(%f, %f) => %f\n", div.name, a, b, (*div.calculate)(a,b));
Output:
```
-pbuetow ~/git/blog/source [38268]% gcc methods-in-c.c -o methods-in-c
-pbuetow ~/git/blog/source [38269]% ./methods-in-c
+pbuetow ~/git/blog/source [38268]% gcc oop-c-example.c -o oop-c-example
+pbuetow ~/git/blog/source [38269]% ./oop-c-example
Multiplication(3.000000, 2.000000) => 6.000000
Division(3.000000, 2.000000) => 1.500000
```
Not complicated at all, but nice to know and helps to make the code easier to read!
-## The flaw
+## That's not OOP, though
However, that's not really how it works in object-oriented languages such as Java and C++. The method call in this example is not a method call as "mult" and "div" in this example are not "message receivers". I mean that the functions can not access the state of the "mult" and "div" struct objects. In C, you would need to do something like this instead if you wanted to access the state of "mult" from within the calculate function, you would have to pass it as an argument:
@@ -75,11 +84,19 @@ However, that's not really how it works in object-oriented languages such as Jav
mult.calculate(mult,a,b));
```
-How to overcome this? You need to take it further.
+## Real object oriented proramming with C
+
+If you want to take it further, hit "Object-Oriented Programming with ANSI-C" into your favourite internet search engine or follow the link below. It goes as far as writing a C preprocessor in AWK, which takes some object-oriented pseudo-C and transforms it to plain C so that the C compiler can compile it to machine code. This is similar to how the C++ language had its origins.
+
+=> https://www.cs.rit.edu/~ats/books/ooc.pdf
+
+## OOP design patterns in the Linux Kernel
+
+Big C software projects, like Linux, also follow some OOP techniques:
-## Taking it further
+=> https://lwn.net/Articles/444910/
-If you want to take it further, type "Object-Oriented Programming with ANSI-C" into your favourite internet search engine, you will find some crazy stuff. Some go as far as writing a C preprocessor in AWK, which takes some object-oriented pseudo-C and transforms it to plain C so that the C compiler can compile it to machine code. This is similar to how the C++ language had its origins.
+C is a very old programming lanuage with it's quirks. This might be one of the reasons why Linux will also let Rust code in.
E-Mail me your comments to paul at buetow dot org!
diff --git a/gemfeed/atom.xml b/gemfeed/atom.xml
index 2c7a597e..07e4b69b 100644
--- a/gemfeed/atom.xml
+++ b/gemfeed/atom.xml
@@ -1,6 +1,6 @@
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
- <updated>2022-01-23T22:20:22+00:00</updated>
+ <updated>2022-01-29T22:10:52+00:00</updated>
<title>foo.zone feed</title>
<subtitle>To be in the .zone!</subtitle>
<link href="gemini://foo.zone/gemfeed/atom.xml" rel="self" />
@@ -1986,21 +1986,29 @@ Total time: 1213.00s
</content>
</entry>
<entry>
- <title>Methods in C</title>
- <link href="gemini://foo.zone/gemfeed/2016-11-20-methods-in-c.gmi" />
- <id>gemini://foo.zone/gemfeed/2016-11-20-methods-in-c.gmi</id>
- <updated>2016-11-20T18:36:51+01:00</updated>
+ <title>Object oriented programming with ANSI C</title>
+ <link href="gemini://foo.zone/gemfeed/2016-11-20-object-oriented-programming-with-ansi-c.gmi" />
+ <id>gemini://foo.zone/gemfeed/2016-11-20-object-oriented-programming-with-ansi-c.gmi</id>
+ <updated>2016-11-20T22:10:57+00:00</updated>
<author>
<name>Paul Buetow</name>
<email>comments@mx.buetow.org</email>
</author>
- <summary>You can do some sort of object oriented programming in the C Programming Language. However, that is very limited. But also very easy and straight forward to use.. .....to read on please visit my site.</summary>
+ <summary>You can do a little of object-oriented programming in the C Programming Language. However, that is, in my humble opinion, limited. It's easier to use a different programming language than C for OOP. But still it's an interesting exercise to try using C for this.. .....to read on please visit my site.</summary>
<content type="xhtml">
<div xmlns="http://www.w3.org/1999/xhtml">
- <h1>Methods in C</h1>
-<p class="quote"><i>Published by Paul at 2016-11-20</i></p>
-<p>You can do some sort of object-oriented programming in the C Programming Language. However, that is very limited. But also very easy and straightforward to use.</p>
-<h2>Example</h2>
+ <h1>Object oriented programming with ANSI C</h1>
+<pre>
+ ___ ___ ____ ____
+ / _ \ / _ \| _ \ / ___|
+| | | | | | | |_) |____| |
+| |_| | |_| | __/_____| |___
+ \___/ \___/|_| \____|
+
+</pre>
+<p class="quote"><i>Published by Paul at 2016-11-20, updated 2022-01-29</i></p>
+<p>You can do a little of object-oriented programming in the C Programming Language. However, that is, in my humble opinion, limited. It's easier to use a different programming language than C for OOP. But still it's an interesting exercise to try using C for this.</p>
+<h2>Function pointers</h2>
<p>Let's have a look at the following sample program. All you have to do is to add a function pointer such as "calculate" to the definition of struct "something_s". Later, during the struct initialization, assign a function address to that function pointer:</p>
<pre>
#include &lt;stdio.h&gt;
@@ -2035,7 +2043,7 @@ int main(void) {
printf("%s(%f, %f) =&gt; %f\n", div.name, a, b, div.calculate(a,b));
}
</pre>
-<p>As you can see, you can call the function (pointed by the function pointer) the same way as in C++ or Java via:</p>
+<p>As you can see, you can call the function (pointed by the function pointer) with the same syntax as in C++ or Java:</p>
<pre>
printf("%s(%f, %f) =&gt; %f\n", mult.name, a, b, mult.calculate(a,b));
printf("%s(%f, %f) =&gt; %f\n", div.name, a, b, div.calculate(a,b));
@@ -2047,20 +2055,24 @@ printf("%s(%f, %f) =&gt; %f\n", div.name, a, b, (*div.calculate)(a,b));
</pre>
<p>Output:</p>
<pre>
-pbuetow ~/git/blog/source [38268]% gcc methods-in-c.c -o methods-in-c
-pbuetow ~/git/blog/source [38269]% ./methods-in-c
+pbuetow ~/git/blog/source [38268]% gcc oop-c-example.c -o oop-c-example
+pbuetow ~/git/blog/source [38269]% ./oop-c-example
Multiplication(3.000000, 2.000000) =&gt; 6.000000
Division(3.000000, 2.000000) =&gt; 1.500000
</pre>
<p>Not complicated at all, but nice to know and helps to make the code easier to read!</p>
-<h2>The flaw</h2>
+<h2>That's not OOP, though</h2>
<p>However, that's not really how it works in object-oriented languages such as Java and C++. The method call in this example is not a method call as "mult" and "div" in this example are not "message receivers". I mean that the functions can not access the state of the "mult" and "div" struct objects. In C, you would need to do something like this instead if you wanted to access the state of "mult" from within the calculate function, you would have to pass it as an argument:</p>
<pre>
mult.calculate(mult,a,b));
</pre>
-<p>How to overcome this? You need to take it further.</p>
-<h2>Taking it further</h2>
-<p>If you want to take it further, type "Object-Oriented Programming with ANSI-C" into your favourite internet search engine, you will find some crazy stuff. Some go as far as writing a C preprocessor in AWK, which takes some object-oriented pseudo-C and transforms it to plain C so that the C compiler can compile it to machine code. This is similar to how the C++ language had its origins.</p>
+<h2>Real object oriented proramming with C</h2>
+<p>If you want to take it further, hit "Object-Oriented Programming with ANSI-C" into your favourite internet search engine or follow the link below. It goes as far as writing a C preprocessor in AWK, which takes some object-oriented pseudo-C and transforms it to plain C so that the C compiler can compile it to machine code. This is similar to how the C++ language had its origins.</p>
+<a class="textlink" href="https://www.cs.rit.edu/~ats/books/ooc.pdf">https://www.cs.rit.edu/~ats/books/ooc.pdf</a><br />
+<h2>OOP design patterns in the Linux Kernel</h2>
+<p>Big C software projects, like Linux, also follow some OOP techniques:</p>
+<a class="textlink" href="https://lwn.net/Articles/444910/">https://lwn.net/Articles/444910/</a><br />
+<p>C is a very old programming lanuage with it's quirks. This might be one of the reasons why Linux will also let Rust code in.</p>
<p>E-Mail me your comments to paul at buetow dot org!</p>
</div>
</content>
diff --git a/gemfeed/index.gmi b/gemfeed/index.gmi
index 07c7b64e..963a84ef 100644
--- a/gemfeed/index.gmi
+++ b/gemfeed/index.gmi
@@ -15,7 +15,7 @@
=> ./2021-04-24-welcome-to-the-geminispace.gmi 2021-04-24 (0802 words) - Welcome to the Geminispace
=> ./2021-04-22-dtail-the-distributed-log-tail-program.gmi 2021-04-22 (2122 words) - DTail - The distributed log tail program
=> ./2018-06-01-realistic-load-testing-with-ioriot-for-linux.gmi 2018-06-01 (2176 words) - Realistic load testing with I/O Riot for Linux
-=> ./2016-11-20-methods-in-c.gmi 2016-11-20 (0318 words) - Methods in C
+=> ./2016-11-20-object-oriented-programming-with-ansi-c.gmi 2016-11-20 (0385 words) - Object oriented programming with ANSI C
=> ./2016-05-22-spinning-up-my-own-authoritative-dns-servers.gmi 2016-05-22 (0512 words) - Spinning up my own authoritative DNS servers
=> ./2016-04-16-offsite-backup-with-zfs-part2.gmi 2016-04-16 (0248 words) - Offsite backup with ZFS (Part 2)
=> ./2016-04-09-jails-and-zfs-on-freebsd-with-puppet.gmi 2016-04-09 (0425 words) - Jails and ZFS with Puppet on FreeBSD