“In reality, programming languages are how programmers express and communicate ideas — and the audience for those ideas is other programmers, not computers. The reason: the computer can take care of itself, but programmers are always working with other programmers, and poorly communicated ideas can cause expensive flops.”
~ Guido van Rossum, in this 2016 article
I’ve mentioned this before, but if you’re interested in learning Lisp/Scheme programming, the makers of gimphelp.org have a nice collection of plugins for Gimp 2.8 that you can download, and they’re all written in Scheme. (Well, a variation of Scheme.)
Here’s the body of a Gimp plugin file named FU_contrast_auto-contrast.scm:
(define (FU-auto-contrast
img
drawable
merge-flag)
(gimp-image-undo-group-start img)
(if (not (= RGB (car (gimp-image-base-type img))))
(gimp-image-convert-rgb img))
; Create a new layer
(define value-layer (car (gimp-layer-copy drawable 0)))
; Give it a name
(gimp-item-set-name value-layer "Contrast Adjustment Layer")
; Add the new layer to the image
(gimp-image-insert-layer img value-layer 0 0)
; Set opacity to 100%
(gimp-layer-set-opacity value-layer 100)
; Set the layer mode to Value
(gimp-layer-set-mode value-layer 14)
; Adjust contrast
(gimp-levels-stretch value-layer)
; Merge down, if required
(if (equal? merge-flag TRUE)
(gimp-image-merge-down img value-layer 1 )
()
)
(gimp-image-undo-group-end img)
(gimp-displays-flush)
)
(script-fu-register "FU-auto-contrast"
"<Image>/Script-Fu/Contrast/Auto Contrast"
"Automatically adjust contrast of drawable"
"Mark Lowry"
"Mark Lowry"
"2006"
"*"
SF-IMAGE "Image" 0
SF-DRAWABLE "Current Layer" 0
SF-TOGGLE "Merge Layers?" FALSE
)
If you’re at least a little comfortable with Lisp/Scheme — and also Gimp — that code is relatively easy to understand. For instance, the define function creates a variable named value-layer, and then other Gimp functions like gimp-item-set-name and gimp-image-insert-layer modify value-layer.
At the end of the code, the script-fu-register shows how to register a plugin so that Gimp will find it and display it in the Gimp menu system.
A few observations come to mind:
1) Like other languages that don’t show their types, you can’t tell value-layer’s type from looking at the code, though you can assume that it’s something like Layer.
2) For some reason Lisp makes it more clear than other languages that you can’t tell what the function parameters are. They’re based on the positions in the list, and seeing "Mark Lowry" in there twice makes you wonder why it’s there twice. The only way to know what the parameters are is (a) guessing by what’s in each field, and (b) looking at the script-fu-register documentation. (This is true in other programming languages, but it really stands out here, possibly because of the formatting.)
If you are looking for Gimp Script-Fu function examples (as I was), the Gimp function examples used in this code are:
gimp-image-undo-group-startgimp-image-convert-rgbgimp-layer-copygimp-item-set-namegimp-image-insert-layergimp-layer-set-opacitygimp-layer-set-modegimp-levels-stretchgimp-image-merge-downgimp-image-undo-group-endgimp-displays-flushscript-fu-registerHere’s the complete source code for this plugin, including the initial comments and license:
; FU_contrast_auto-contrast.scm
; version 2.9 [gimphelp.org]
; last modified/tested by Paul Sherman
; 02/15/2014 on GIMP-2.8.10
;
; 02/15/2014 - convert to RGB if needed
;==============================================================
;
; Installation:
; This script should be placed in the user or system-wide script folder.
;
; Windows Vista/7/8)
; C:\Program Files\GIMP 2\share\gimp\2.0\scripts
; or
; C:\Users\YOUR-NAME\.gimp-2.8\scripts
;
; Windows XP
; C:\Program Files\GIMP 2\share\gimp\2.0\scripts
; or
; C:\Documents and Settings\yourname\.gimp-2.8\scripts
;
; Linux
; /home/yourname/.gimp-2.8/scripts
; or
; Linux system-wide
; /usr/share/gimp/2.0/scripts
;
;==============================================================
;
; LICENSE
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
;==============================================================
; Original information
;
; Automatically adjusts contrast of the current
; drawable by duplicating the layer, setting the
; new layer to Value blend mode, then running
; Auto Levels on the Value layer.
;==============================================================
(define (FU-auto-contrast
img
drawable
merge-flag
)
(gimp-image-undo-group-start img)
(if (not (= RGB (car (gimp-image-base-type img))))
(gimp-image-convert-rgb img))
; Create a new layer
(define value-layer (car (gimp-layer-copy drawable 0)))
; Give it a name
(gimp-item-set-name value-layer "Contrast Adjustment Layer")
; Add the new layer to the image
(gimp-image-insert-layer img value-layer 0 0)
; Set opacity to 100%
(gimp-layer-set-opacity value-layer 100)
; Set the layer mode to Value
(gimp-layer-set-mode value-layer 14)
; Adjust contrast
(gimp-levels-stretch value-layer)
; Merge down, if required
(if (equal? merge-flag TRUE)
(gimp-image-merge-down img value-layer 1 )
()
)
(gimp-image-undo-group-end img)
(gimp-displays-flush)
)
(script-fu-register "FU-auto-contrast"
"<Image>/Script-Fu/Contrast/Auto Contrast"
"Automatically adjust contrast of drawable"
"Mark Lowry"
"Mark Lowry"
"2006"
"*"
SF-IMAGE "Image" 0
SF-DRAWABLE "Current Layer" 0
SF-TOGGLE "Merge Layers?" FALSE
)
I just spent 45 minutes reading a new book about a programming language I was excited to learn, then slammed it shut and said, “Poorly organized, too many words, not enough code.”
That’s always such a disappointing feeling when you have that initial excitement about a programming language (or technology), and then a book is such a letdown. (I really hope people don’t view my books that way.)
I saw this definition of type safety yesterday in a book named Programming TypeScript and I thought it was very simple and good:
Type Safety: Using types to prevent programs from doing invalid things.
Kent Beck has a good article on Medium titled, Programmer Test Principles.
I had never heard of the term “Yoda Conditions” until now, but I have seen them in some Java code where programmers put the constant first in an effort to avoid null pointer exceptions.
(image adapted from codinghorror.com)
Famed programmer Joe Armstrong passed away this weekend. He created the Erlang programming language, based on the actor model, and without using Google, I’m pretty darned sure that Erlang had an impact on Akka, the very cool actor library for Scala. Here’s an article Mr. Armstrong wrote some years ago, titled, Why OO Sucks (OO as in OOP).
“Write shy code — modules that don’t reveal anything unnecessary to other modules and that don’t rely on other modules’ implementations.”
~ Dave Thomas
I saw this “SQL joins as Venn diagrams” image on this Twitter page. To give attribution to the original author, it appears to have been created by C.L. Moffatt and documented in this Visual Representation of SQL Joins article. However, this article makes the case that Venn diagrams are not an accurate description of SQL joins.
“The sooner you start to code, the longer the program will take.”
~ Roy Carlson (which I saw in this tweet)
In general, I’m a fan of that quote, meaning that the harder the problem is, the more I like to find a whiteboard or some index cards to work through the problem that way before I start coding.
“Testing takes time, just like structural analysis takes time. Both activities ensure the quality of the end product. It’s time for software developers to take up the mantle of responsibility for what they produce. Testing alone isn’t sufficient, but it is necessary.”
~ Neal Ford (as seen on this tweet)
This Wikipedia page on continuous integration is actually a good resource for computer programming best practices.
twobithistory.org has a nice story about Lisp titled, How Lisp became God’s own programming language. That page links to Paul Graham’s old Beating the averages post where he shares this Eric Raymond quote: “Lisp is worth learning for the profound enlightenment experience you will have when you finally get it; that experience will make you a better programmer for the rest of your days, even if you never actually use Lisp itself a lot.”
A friend of mine is an honest reviewer of apps. When I asked her to use the AAA iOS app while we were driving back from Florida, she said, “OMG, please don’t make me use that piece of crap again.”
From this AirBnB article about using React Native: “JavaScript is an untyped language. The lack of type safety was both difficult to scale and became a point of contention for mobile engineers used to typed languages who may have otherwise been interested in learning React Native ... A side-effect of JavaScript being untyped is that refactoring was extremely difficult and error-prone.”
The 90/90 Rule: “The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time.”
~ Tom Cargill
Here’s An Illustrated Proof of the CAP Theorem, if you’re into things like consistency, availability, partition tolerance, and distributed systems.
Based on his current work in developing Rust, Aaron Turon has a couple of good blog posts on developing/leading open source projects titled, listening and trust, part1, and listening and trust, part 2.
I just came across a couple more null values out in the wild, this time on the espn.com website.