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A.Lazebny. Mysteries of Autodesk's Caves

Part 7. Secrets of ACAD_EVALUATION_GRAPH room

Many users tried many times to swap parameter names in the block properties list but with no success. In what sequence these parameters were created - in that sequence they were displayed. My first task was to swap parameters.

As I have already written by swapping 95th pairs I razed all. Then I swapped two whole records but they returned to their places. Then I swapped only record numbers - numbers returned to theirs places and swapped records. Aha, I think, it is a step forward. Looked at block properties list - no visible changes. How is that? I changed dictionary in fact, hence somewhere something should vary! I got angry and started pestering block. I began with the swapped property. I opened the door leading to that room and dully made Entmod to all the room (entmod in AutoLISP means "modify entity"). AutoCAD swore - he said that dotted pairs like 1071 and 1010 were unknown. I removed them and made Entmod again. I see - hurrah! Block properties have swapped places!

Now I'll do a digression. The point is that there is such an incantation (it is rather intricate so I will miss it) that gets all the properties list for the dynamic block - but after swapping block properties the list remained unchanged! Then I shaked the whole block having made Entmod to it. And after that everything changed everywhere as it should be.

Now, after long time I think that I would probably shake the whole block at once? I don't know. Let another digger test this.

My second sick callus was that block editor allowed only one Visibility Set. If you have for examle 10 objects that you want to see in all different visibility states then you must describe 1024 visibilities. And if one could insert many Visibility Sets then having taken 10 sets you would need to describe object visibilty only in one of them, that is 10 times instead of 1024. And as one Visibility Set can describe visibility for a group of elements the total number of combinations is beyond all mind calculations.

I tried to create a new Visibility Set parameter and created it as a copy of an existing one. Inserted. My block acquired an amazing quality. If I come in there is no Visibility Set. If I come out it exists in model and in block properties. I come in again - none. I set a new one - it is taken. I come out - one more appeared. I come in - again desappeared. And so on ad infinitum. Thus I conclude that I may have many such parameters.

After some time I removed my "clumsy" Visibility Set and - oh, wonder! Block editor saw the first in order Visibility Set. Moreover editor began to work with it as it should. And since I was already able to swap places of block property parameters it turned out that moving to very top any of added Visibility Sets alows to edit it with block editor.

I think that I made not a "clumsy" Visibility Set but AutoCAD correctly inserts only its own-made parameters and my dummies simply confuse AutoCAD. But it gave some harvest. In such a form my incantations work. Firstly I do a dummy then I put it to AutoCAD whose head gets confused and it allows to add one more parameter, and when I remove my dummy, AutoCAD recovers and allows to add parameter and when I remove my dummy AutoCAD comes to its senses, but it cannot undo and is to handle what it made itself.

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