Globalget and globalput function in PyTeal and branching IF

General
,
1

Hi everybody,
I have a problem in a Smart Contract: because of some operations, I could have some negative values, so, to avoid this problem, for any operations, like x = v1-h I want the absolute value. So, using the function globalput and globalget, I tried this:

If(Lt(v1, h),
       App.globalPut(Bytes("negative"), Bytes("1")),
       App.globalPut(Bytes("negative"), Bytes("0"))
       )
negative = App.globalGet(Bytes("negative"))


If(Eq(negative, Bytes("1")),
       App.globalPut(Bytes("x"), h - v1),
       App.globalPut(Bytes("x"), v1 - h)
)
x = App.globalGet(Bytes("x"))

Where I check h = 1581 and v1 = 0, but negative = 0.
I tried this with Int(1) and Int(0) too instead of Bytes(“1”) and Bytes(“0”).

What’s the problem?

1 Like
2

This is indeed strange.
Did you try to debug it step by step using dry run or tealdbg https://developer.algorand.org/docs/features/asc1/debugging ?

3

Through dryrun I get this error: invalid : 33 app_global_get not allowed in current mode.
I hope I’ve used dry run in the right way.

4

I wouldn’t use globalPut and globalGet is this task:

$ cat lt.py
from pyteal import *

def Abs_diff(a: Expr, b: Expr) -> TealType.uint64:
    return If (Lt(a, b), b-a, a-b)


abs_diff_1 = Abs_diff(Int(33), Int(22))
abs_diff_2 = Abs_diff(Int(55), Int(11))


a = ScratchVar(TealType.uint64)
b = ScratchVar(TealType.uint64)
abs_diff_3 = Abs_diff(a.load(), b.load())

program = Seq([
    Assert(abs_diff_1 == Int(11)),
    Assert(abs_diff_2 == Int(44)),
    a.store(Int(222)),
    b.store(Int(333)),
    Assert(abs_diff_3 == Int(111)),
    Int(1)
])

print(compileTeal(program, mode=Mode.Application, version=3))


$ cat comp.sh
#!/bin/bash

gcmd="~/n_test1/goal -d ~/n_test1/data_testnet"

python3 lt.py > lt.teal
CONTRACT_ADDR=`eval $gcmd clerk compile lt.teal | awk '{ print $2 }'`
echo "Contract address: $CONTRACT_ADDR"

eval $gcmd clerk send -f $CONTRACT_ADDR -t $CONTRACT_ADDR -a 0 -o tx0.tx
eval $gcmd clerk sign -p lt.teal -i tx0.tx -o stx0.tx
eval $gcmd clerk dryrun -t stx0.tx


$ ./comp.sh
Contract address: MMTL7BRLMSNRWMBGZ44PNZ76LIFFFUHYBCAWBO2ZSJ5LXEELGXNQD7OV6A
tx[0] cost=48 trace:
  1 intcblock => <empty stack>
 14 intc_0 => (33 0x21) 
 15 intc_1 => (22 0x16) 
 16 < => (0 0x0) 
 17 bnz => <empty stack>
 20 intc_0 => (33 0x21) 
 21 intc_1 => (22 0x16) 
 22 - => (11 0xb) 
 23 b 0x00 0x03 => (11 0xb) 
 29 intc_2 => (11 0xb) 
 30 == => (1 0x1) 
 31 assert => <empty stack>
 32 intc_3 => (55 0x37) 
 33 intc_2 => (11 0xb) 
 34 < => (0 0x0) 
 35 bnz => <empty stack>
 38 intc_3 => (55 0x37) 
 39 intc_2 => (11 0xb) 
 40 - => (44 0x2c) 
 41 b 0x00 0x03 => (44 0x2c) 
 47 intc 0x04 => (44 0x2c) 
 49 == => (1 0x1) 
 50 assert => <empty stack>
 51 intc 0x05 => (222 0xde) 
 53 store 0x00 => <empty stack>
 55 intc 0x06 => (333 0x14d) 
 57 store 0x01 => <empty stack>
 59 load 0x00 => (222 0xde) 
 61 load 0x01 => (333 0x14d) 
 63 < => (1 0x1) 
 64 bnz => <empty stack>
 75 load 0x01 => (333 0x14d) 
 77 load 0x00 => (222 0xde) 
 79 - => (111 0x6f) 
 80 intc 0x07 => (111 0x6f) 
 82 == => (1 0x1) 
 83 assert => <empty stack>
 84 intc 0x08 => (1 0x1) 

 - pass -
5

I realized that your code might not work because PyTEAL does not execute everything line by line.
Concretely, on @Maugli’s solution, if the last part of the PyTEAL program was:

print(compileTeal(abs_diff_3, mode=Mode.Application, version=3))

instead of

print(compileTeal(program, mode=Mode.Application, version=3))

then abs_diff_1 and abs_diff_2 would never be computed. And if they involved storing state, this state would never be stored.

Concretely, what argument did you give to compileTeal?

6

My code is in an approval_program function, so my last call is compiled = compileTeal(approval_program(), Mode.Application)

7

But what does your approval_program() look like? You can remove the parts you want to hide, but keep the general structure.