Introduction
Different from transactions without assignment operators, the | assignment operator in front of the transaction symbol will assume the following rules focussing on overlaying data from the source variable in the destination variable:
- Transactions can be carried out on base variables as well as member variables.
- If the destination variable does not yet exist, then it will be created as simple variable containing void value before the transaction begins. However, the source variable on the right-hand side must exist.
- The existing setup of structure and array members and sub-members in the destination variable may be extended:
- Further arrays and/or structures may be added.
- Additional members may be added to existing arrays and/or structures.
- Destination memebers for which equivalent source members are existing will be overwritten.
- Where possible, all structure and array members and sub-members of the source variable will be included in the transaction.
- The base variable of the specified destination will be overwritten if the ^ suffix is not used.
Following actions are applied on the destination variables using this assignment operator:
| Destination | Source | Description |
|---|---|---|
| Simple or zero members | Simple or zero members | The value of the base variable will be transferred as long no ^ suffix is specified. |
| Simple or zero members | Array | Base variable: See above. The array (including sub-members) will be transferred. |
| Simple or zero members | Structure | Base variable: See above. The structure (including sub-members) will be transferred. |
| Structure | Simple or zero members | Base variable: See above. |
| Structure | Array | Base variable: See above. The array members will be renamed to structure members where the member names are 8-digit text representations of the index number, e.g. '00000000', '00000001', etc. After this, same rules as for structures described below apply. |
| Structure | Structure | Base variable: See above. The structure (including sub-members) will be transferred. - Existing members will be overwritten - Additional members may be added - Additional arrays and/or structures may be added |
| Array | Simple or zero members | Base variable: See above. |
| Array | Array | Base variable: See above. The array will be copied. - If the destination has more members than the source, then the excess destination members remain unaffected. - If the destination has fewer members than the source, then the array will be extended in order to transfer all members. |
| Array | Structure | Base variable: See above. The members for which corresponding member positions are already existing in the destination variable will also be transferred. The existing array members will be replaced by structure members from the source variable, sorted in alphabetic order by member names. - If the destination has more members than the source, then the excess destination members remain unaffected. - If the destination has fewer members than the source, then the array will be extended in order to transfer all members. |
Copy Transaction Example
structure( animals1[], { mammal, bird, fish }, { dog, owl, eel} );
structure( animals1[mammal], { carnivore, herbivore }, { bear, deer } );
structure( animals2[], { mammal, fish, reptile }, { cat, trout, turtle } );
structure( animals2[mammal], { carnivore, omnivores }, { lynx, skunk } );
animals1[] |<== animals2[]; // animals1 contains overwritten fish, reptile and all mammal sub-members
see(animals1[]);animals1[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish trout (softquoted string,full access)
mammal cat (softquoted string,full access)
carnivore lynx (softquoted string,full access)
herbivore deer (softquoted string,full access)
omnivores skunk (softquoted string,full access)
reptile turtle (softquoted string,full access)
Copy Transaction Example among Structures and Arrays
structure( animals1[], { mammal, bird, fish }, { dog, owl, eel} );
structure( animals1[mammal], { herbivore, carnivore }, { deer, bear } );
structure( animals2[], { mammal, fish, reptile }, { cat, trout, turtle } );
array( animals2[mammal], { lynx, skunk, shark, pig } );
animals2[] |<== animals1[]; // Note: bear, then deer replace lynx and skunk
animals1[] |<== animals2[];
see(animals2[]); // Array with 4 elements
see(animals1[]); // Addition of beer, dear, shark and piganimals2[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish eel (softquoted string,full access)
mammal dog (softquoted string,full access)
Array [ 0] bear (softquoted string,full access)
Array [ 1] deer (softquoted string,full access)
Array [ 2] shark (softquoted string,full access)
Array [ 3] pig (softquoted string,full access)
reptile turtle (softquoted string,full access)
animals1[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish eel (softquoted string,full access)
mammal dog (softquoted string,full access)
00000000 bear (softquoted string,full access)
00000001 deer (softquoted string,full access)
00000002 shark (softquoted string,full access)
00000003 pig (softquoted string,full access)
carnivore bear (softquoted string,full access)
herbivore deer (softquoted string,full access)
reptile turtle (softquoted string,full access)
Move Transaction Example
structure( animals1[], { mammal, bird, fish }, { dog, owl, eel} );
structure( animals1[mammal], { carnivore, herbivore }, { bear, deer } );
structure( animals2[], { mammal, fish, reptile }, { cat, trout, turtle } );
structure( animals2[mammal], { carnivore, omnivores }, { lynx, skunk } );
animals1[mammal] |<<= animals2[mammal];
// Lynx replaces bear, skunk added, turtle added
see(animals1[]); // omnivore added, carnivore overwritten
see(animals2[]); // no more mammal subtypes (...vores)animals1[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish eel (softquoted string,full access)
mammal cat (softquoted string,full access)
carnivore lynx (softquoted string,full access)
herbivore deer (softquoted string,full access)
omnivores skunk (softquoted string,full access)
animals2[] [Void] (void,full access)
fish trout (softquoted string,full access)
reptile turtle (softquoted string,full access)
Swap Transaction Example
structure( animals1[], { mammal, bird, fish }, { dog, owl, eel} );
structure( animals1[mammal], { carnivore, herbivore }, { bear, deer } );
structure( animals2[], { mammal, fish, reptile }, { cat, trout, turtle } );
structure( animals2[mammal], { carnivore, omnivores }, { lynx, skunk } );
animals1[] |<=> animals2[];
see(animals1[]); // trout and eel; and dog and cat are exchanged, owl and turtle duplicated
see(animals2[]); animals1[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish trout (softquoted string,full access)
mammal cat (softquoted string,full access)
carnivore lynx (softquoted string,full access)
herbivore deer (softquoted string,full access)
omnivores skunk (softquoted string,full access)
reptile turtle (softquoted string,full access)
animals2[] [Void] (void,full access)
bird owl (softquoted string,full access)
fish eel (softquoted string,full access)
mammal dog (softquoted string,full access)
carnivore bear (softquoted string,full access)
herbivore deer (softquoted string,full access)
omnivores skunk (softquoted string,full access)
reptile turtle (softquoted string,full access)