[Toaster] general solution proposed for 7394 "Toaster needs to add a space to the value of IMAGE_INSTALL_append"

[Reyna, David]

Hi Alex, Belén, and all,

I am looking at 7394, and while I can hard code something for "IMAGE_INSTALL_append", it will instantly break once anyone tries to introduce any other variable that need special handling.

I would like instead to propose a general but simple solution to cover all the usual cases, with no hard-coding, and about the same amount of code complexity that the limited solution would require.

1) Here is my source information about ways variables can be manipulated http://elinux.org/Bitbake_Cheat_Sheet, for example:

  VAR = "foo"   simple assignment
  VAR ?= "foo"  assign if no other value is already assigned (default assignment)
  VAR += "foo"  append with space
  VAR =+ "foo"  prepend with space
  VAR .= "foo"  append without space
  VAR =. "foo"  prepend without space
  VAR_append = "foo"    append without space

You will observe that currently we (a) really only cover simple assignments, and (b) the trick with the IMAGE_INSTALL having "_append" is in fact misleading, since it does not line up with the bitbake syntax which would indicate that _no_ space would be added - so wrong for IMAGE_INSTALL.

2) Here is my proposed solution

  (a) Allow variables to have the following suffixes that align with the common bitbake operators:

  VAR        | simple assignment
  VAR?=      | assign if no other value is already assigned
  VAR+=      | append with space
  VAR=+      | prepend with space
  VAR.=      | append without space
  VAR=.      | prepend without space
  VAR_append | append without space

  (b) In "writeConfFile()" in the file "bitbake/lib/toaster/bldcontrol/localhostbecontroller.py", change the code to swap in the respective operator in place of "=".

  (c) In the configure variable page change the javascript variable name validation code to allow these specific suffixes (plus the error messages).

In fact what we can do is have a pull down list in the page to specific and select any of the supported special operators, and let the javascript manipulate these special syntaxes. That way no one needs to memorize/learn about the supported operators, making the whole thing more intuitive and self-directed.

  (d) Change the core variable  "IMAGE_INSTALL_append" to "IMAGE_INSTALL+=" to take advantage of this new facility and resolve the original defect (this name change would be in the JSON file and in the view class).

  (e) Finally, send the documentation on this to Scott.

Is this acceptable? It would be easy to implement, and I think a lot more scalable, useful, and correct.

- David


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