Explode Blocks using VBA but program loops
Let me see if I understand you correctly: your ultimate goal is to purge certain layer. So, you have already made sure there is no entity on that layer, but there is block definition which contains entity (or entities that is/are on that layer). So, you need to first erase all block references to that block definition, so that you can purge that block definition, then in turn you can finally purge the layer.
If this is what you need to do, why do you need to explode block reference before erasing? You simply erase all the block references to that block definition and then call Purge once, which would purge the block definition so that the layer held up by the block definition is freed. Then call Purge again would purge the layer.
For your code, you seem to explode all block references and then erase them. Does that imply that all block definitions in the drawing somehow hold the layer in them? If so, it seems that the drawing is used as "base drawing" really should be cleaned up, rather than each time it is used first and running code to clean it up up on use.
I am still a bit confused: if the goal is to purge an unwanted layer, why do you need to explode block reference?
See, a layer could not be purged/deleted if any entity is on that layer. There could be 2 situations that hold a layer up: entities (either in ModelSpace or PaperSpace) sitting on that layer, including block references; or a BLOCK DEFINITION that consists of entities on that layer. For the former, you only need to erase them to free up the later. For the latter, even no block references to the block definition exists, the block definition still holds up the layer. So, you need to purge the block definition (of course you need to erase all its references) first. Then you can finally purge the layer in interest. So where does the "exploding" need come into play here?
If I understand your need correctly (purging certain layer or layers), I'd do these:
1. Loop through ModelSpace and all layouts (PaperSpaces) to search entities on that layer(s). If found, erase them. You can also create SelectSet with layer(s) filter to select all entities in drawing and erase them;
2. Loop through all block definitions of the drawing (AcadDocument.Blocks), for each block definition (AcadBlock), loop through its entities inside to check the Layer property. If the layer is the target layer(s), that block has to be purged. Therefore, you search the ModelSpace/PaperSpaces again for the block references to that block definition. If found (regardless the block reference sitting on which layer itself), erase it. Finally the block definition will no longer referenced.
3. Call AcadDocument.PurgeAll() method at least 2 times, the first would purge the block definitions that hold up the layer(s), and the second time the layer(s) in interest would be purged. However, calling PurgeAll() would purge other Blocks/Layers... that you do not want to purge. Alternatively, you can simply call AcadBlock.Delete() and AcadLayer.Delete() as long as they become delete-able (after the block definition is reference-free and the layer is hold-free).
@JustinSider wrote:
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Your point number 2, you say loop through the blocks entities inside so this means essentially opening up a block and changing the layers? If I could include this code with what I have somehow this would be great. I know my code isn't perfect, I'm a beginner but I know it works.
My point is that beside the visible entities (on ModelSpace or in Layouts) that may reside on the layer you want to delete, there are "inivisible" entities in various block definition that also associated to that layer, thus make that layer not delete-able. Therefore, simply change all visible entities' layer (or erase these entities) may not enough to release the layer for deleting. So, you need to check each block definitions (except for *Model_Space" and "*Paper_Spacex" block) to see if any entity in the block definition is associated to the layer. If yes, you can either change the block definition (i.e. change the entity's layer in the block definition), or you can erase the block definition (but you need to erase all the block's references).
Attached some VBA code and an example drawing to demonstrate how to do it in following scenario:
1. A drawing has a block definition containing 3 entities: one on layer 0, one on layer1, and one on layer2. Then 3 block references to this block definition are inserted on layer 0, layer 1 and layer2. There are also 3 circle drawn on layer 0, layer1 and layer2.
2. I want to delete layer1 and layer2. Obviously I cannot, even I deleted the 2 circles on layer1 and layer2 and 2 block references on layer1 and layer2 (so, no visible entity sits on layer1 and layer2), because layer1 and layer2 are still referred in the block definition.
3. So, I need to examine all block definitions to see if the 2 layers are referred in them. For each block definition found with the 2 layers referred, I first search the drawing to delete all the block reference, then I can delete the block definition, thus free the 2 layers from the block definitions.
4. After doing this, I can finally make sure the layers are not referred to by any entity, be it in visible spaces, or in block definitions, then I can delete it.
5. I could have call PurgeAll(), but it might not be good if you still want to keep other purge-bale objects (linetypes, text styles...) in drawing, but only want to purge certain layer, my code is the customized "purge" only target particular objects (2 layers, here).
6. Also pay attention: if the drawing has entities not only in ModelSpace, but also various Layouts, the code would also need to search entities/block reference in Layouts... But you get the idea.
HTH
P.S. Somehow I cannot post the reply with attachment of *.7z file. So I renamed it as "DeleteLayer.7z.RAR". You would need to rename it back to "DeleteLayer.7z" after download it.