Blob Modification, Identity, and Variable Storage; Expression Syntax

is similar to zero. Omitting the last index is similar to -1. > :let endblob = myblob[2:] " from item 2 to the end: 0z2233 :let shortblob = myblob[2:2] " Blob with one byte: 0z22 :let otherblob = myblob[:] " make a copy of the Blob If the first index is beyond the last byte of the Blob or the second index is before the first index, the result is an empty Blob. There is no error message. If the second index is equal to or greater than the length of the Blob the length minus one is used: > :echo myblob[2:8] " result: 0z2233 Blob modification ~ *blob-modification* To change a specific byte of a blob use |:let| this way: > :let blob[4] = 0x44 When the index is just one beyond the end of the Blob, it is appended. Any higher index is an error. To change a sequence of bytes the [:] notation can be used: > let blob[1:3] = 0z445566 The length of the replaced bytes must be exactly the same as the value provided. *E972* To change part of a blob you can specify the first and last byte to be modified. The value must have the same number of bytes in the range: > :let blob[3:5] = 0z334455 To add items to a Blob in-place, you can use |:let+=| (|blob-concatenation|): > :let blobA = 0z1122 :let blobA += 0z3344 < When two variables refer to the same Blob, changing one Blob in-place will cause the referenced Blob to be changed in-place: > :let blobA = 0z1122 :let blobB = blobA :let blobB += 0z3344 :echo blobA 0z11223344 < You can also use the functions |add()|, |remove()| and |insert()|. Blob identity ~ Blobs can be compared for equality: > if blob == 0z001122 And for equal identity: > if blob is otherblob < *blob-identity* *E977* When variable "aa" is a Blob and you assign it to another variable "bb", both variables refer to the same Blob. Then the "is" operator returns true. When making a copy using [:] or |copy()| the values are the same, but the identity is different: > :let blob = 0z112233 :let blob2 = blob :echo blob == blob2 < 1 > :echo blob is blob2 < 1 > :let blob3 = blob[:] :echo blob == blob3 < 1 > :echo blob is blob3 < 0 Making a copy of a Blob is done with the |copy()| function. Using [:] also works, as explained above. 1.6 More about variables ~ *more-variables* If you need to know the type of a variable or expression, use the |type()| function. When the '!' flag is included in the 'shada' option, global variables that start with an uppercase letter, and don't contain a lowercase letter, are stored in the shada file |shada-file|. When the 'sessionoptions' option contains "global", global variables that start with an uppercase letter and contain at least one lowercase letter are stored in the session file |session-file|. variable name can be stored where ~ my_var_6 not My_Var_6 session file MY_VAR_6 shada file It's possible to form a variable name with curly braces, see |curly-braces-names|. ============================================================================== 2. Expression syntax *expression-syntax* Expression syntax summary, from least to most significant: |expr1| expr2 expr2 ? expr1 : expr1 if-then-else |expr2| expr3 expr3 || expr3 ... logical OR |expr3| expr4 expr4 && expr4 ... logical AND |expr4| expr5 expr5 == expr5 equal expr5 != expr5 not equal expr5 > expr5 greater than expr5 >= expr5 greater than or equal expr5 < expr5 smaller than expr5 <= expr5 smaller than or equal expr5 =~ expr5 regexp matches expr5 !~ expr5 regexp doesn't match expr5 ==? expr5 equal, ignoring case expr5 ==# expr5 equal, match case etc. As above, append ? for ignoring case, # for matching case expr5 is expr5 same |List|, |Dictionary| or |Blob| instance expr5 isnot expr5 different |List|, |Dictionary| or |Blob| instance |expr5| expr6 expr6 + expr6 ... number addition, list or blob concatenation expr6 - expr6 ... number subtraction expr6 . expr6 ... string concatenation expr6 .. expr6 ... string concatenation |expr6|

This section details blob modification by replacing bytes and adding items, including the effects of in-place changes on variables referencing the same blob. It covers blob identity, explaining how the 'is' operator checks for the same blob instance, while copying creates distinct instances with equal values. The section briefly touches on variable types, shada file, and session file storage. Finally, it summarizes Vim's expression syntax, listing operators from least to most significant, covering conditional expressions, logical operators, comparison operators (including case-sensitive and case-insensitive options), and concatenation.