Editing Configuration Files For Python
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− | This is an article started by Russ Hensel, see "http://www.opencircuits.com/index.php?title=Russ_hensel#About My Articles" About My Articles for a bit of info. | + | This is an article started by Russ Hensel, see "http://www.opencircuits.com/index.php?title=Russ_hensel#About My Articles" About My Articles for a bit of info. The page is only partly finished. |
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= Why Configuration Files = | = Why Configuration Files = | ||
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== How: The Basics == | == How: The Basics == | ||
− | No matter what the application I put the configuration in a file called parameters.py and use it to define/create a class called Parameters. It is full of instance variables like self.logging_id = "MyLoggingId". Any part of my system that wants to know a parameter value takes the instance of Parameters created at startup and accesses its instance value | + | No matter what the application I put the configuration in a file called parameters.py and use it to define/create a class called Parameters. It is full of instance variables like self.logging_id = "MyLoggingId". Any part of my system that wants to know a parameter value takes the instance of Parameters created at startup and accesses its instance value logging_id = system_parameter.logging_id. It is very easy. |
− | You may ask how does | + | You may ask how does that part of the system get the instance of of parameters? The best way is probably through a global singleton. It is more or less what I do. There seem to be a host of methods of implementing singletons. I use a little recommended one but one that I find more than adequate: I define a class and make the global variables be variables of the class not the instance. You can get access to the class just by importing it, creating an instance servers no particular purpose. So the global class, AppGlobal, is defined something like this ( in a file app_global.py ) |
<pre> | <pre> | ||
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If you are asking why Parameters is not all defined at a Class level instead of instance level it is because I did not think of it then, I am now but have not changed the code so far ( requires more thought ). | If you are asking why Parameters is not all defined at a Class level instead of instance level it is because I did not think of it then, I am now but have not changed the code so far ( requires more thought ). | ||
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== How: More Advanced == | == How: More Advanced == | ||
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At some later point I may not remember well which grouping I used so I often give them names as in self.connect = "Remote" in the example. | At some later point I may not remember well which grouping I used so I often give them names as in self.connect = "Remote" in the example. | ||
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=== Conditionally Assign Values === | === Conditionally Assign Values === | ||
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=== My Overall Structure === | === My Overall Structure === | ||
− | + | * Meet the syntactic requirements for class creation. | |
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− | * Meet the syntactic requirements for class | ||
* Assign instance to AppGlobal | * Assign instance to AppGlobal | ||
− | * Call a subroutine that defaults all value as best it can | + | * Call a subroutine that defaults all value as best it can ( including getting OS and computer name ) |
− | * Call a subroutine that tweaks values according to | + | * Call a subroutine that tweaks values according to OS |
− | * Call a subroutine at give a value to mode and sets the mode of operation that has the name self.mode | + | * Call a subroutine that tweaks values according to computer name |
+ | * Call a subroutine at give a value to mode and sets the mode of operation that has the name self.mode | ||
* Done | * Done | ||
− | Code discipline is such that other code never | + | Code discipline is such that other code never touches these values again ( except for some cute little monkey patching that I currently do not use and do not want to explain ). |
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== Why Advantages/Features == | == Why Advantages/Features == | ||
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= Editing and Editors = | = Editing and Editors = | ||
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You need a text editor suitable for .py files to manage the parameter file ( parameters.py ) | You need a text editor suitable for .py files to manage the parameter file ( parameters.py ) | ||
This includes most text editors. I particularity like: | This includes most text editors. I particularity like: | ||
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* Python cares about capitalization, use the capitalization indicated in the default files and the example code. | * Python cares about capitalization, use the capitalization indicated in the default files and the example code. | ||
* Python also cares a lot about how lines are indented. Do not change the indentation from the sample files, and always indent using spaces ( not tabs. most text editors will use spaces automatically for .py files, even if you use the tab key ) | * Python also cares a lot about how lines are indented. Do not change the indentation from the sample files, and always indent using spaces ( not tabs. most text editors will use spaces automatically for .py files, even if you use the tab key ) | ||
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+ | == Modes == | ||
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+ | Modes are a set of parameters you may want to use for a specialization of the application, this may be to adapt the application to a particular environment or user. Because of this the first method in parameters.py is normally choose_mode. It has calls to the modes in your parameter file ( except the default mode that is called prior to choose mode ). Normally all but the mode you want are commented out. There is also a mode at the end, plus_test_mode that is used to temporarily modify another mode. So once you have you system set up you will most often just switch modes using choose_mode. | ||
= Other Links = | = Other Links = | ||
− | + | '''*Check out link to left "What links here"''' | |
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*'''[https://param.pyviz.org/ Param — Param 1.9.0 documentation ]''' | *'''[https://param.pyviz.org/ Param — Param 1.9.0 documentation ]''' | ||
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[[Category:Arduino/RaspberryPi]][[Category:Python]][[Category:SmartTerminal]][[Category:Python SmartPlug]] [[Category:Python Easy DB]] [[Category:Python Projects]] | [[Category:Arduino/RaspberryPi]][[Category:Python]][[Category:SmartTerminal]][[Category:Python SmartPlug]] [[Category:Python Easy DB]] [[Category:Python Projects]] | ||
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